<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
    <!-- Field: Doc-Info; Name: Generator; Value: GoFiler Complete; Version: 6.0b -->
    <!-- Field: Doc-Info; Name: VendorURI; Value: https://www.novaworks.com -->
    <!-- Field: Doc-Info; Name: Status; Value: 0x00000000 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrli="http://www.xbrl.org/2003/instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
    <link:roleRef roleURI="http://NTHI/role/Cover" xlink:href="nthi-20250331.xsd#Cover" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/BalanceSheets" xlink:href="nthi-20250331.xsd#BalanceSheets" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/BalanceSheetsParenthetical" xlink:href="nthi-20250331.xsd#BalanceSheetsParenthetical" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/StatementsOfOperations" xlink:href="nthi-20250331.xsd#StatementsOfOperations" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/StatementsOfChangesInShareholdersDeficitUnaudited" xlink:href="nthi-20250331.xsd#StatementsOfChangesInShareholdersDeficitUnaudited" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/StatementsOfCashFlows" xlink:href="nthi-20250331.xsd#StatementsOfCashFlows" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/DescriptionOfBusinessAndLiquidity" xlink:href="nthi-20250331.xsd#DescriptionOfBusinessAndLiquidity" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/BasisOfPresentationAndSummaryOfSignificantAccountingPolicies" xlink:href="nthi-20250331.xsd#BasisOfPresentationAndSummaryOfSignificantAccountingPolicies" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/RelatedPartyTransactions" xlink:href="nthi-20250331.xsd#RelatedPartyTransactions" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/RelatedPartyLoansPayable" xlink:href="nthi-20250331.xsd#RelatedPartyLoansPayable" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/Leases" xlink:href="nthi-20250331.xsd#Leases" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/CommonAndPreferredStock" xlink:href="nthi-20250331.xsd#CommonAndPreferredStock" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/SegmentReporting" xlink:href="nthi-20250331.xsd#SegmentReporting" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/Stock-basedCompensation" xlink:href="nthi-20250331.xsd#Stock-basedCompensation" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/CommitmentsAndContingencies" xlink:href="nthi-20250331.xsd#CommitmentsAndContingencies" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/SubsequentEvents" xlink:href="nthi-20250331.xsd#SubsequentEvents" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies" xlink:href="nthi-20250331.xsd#BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/RelatedPartyLoansPayableTables" xlink:href="nthi-20250331.xsd#RelatedPartyLoansPayableTables" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/CommonAndPreferredStockTables" xlink:href="nthi-20250331.xsd#CommonAndPreferredStockTables" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/SegmentReportingTables" xlink:href="nthi-20250331.xsd#SegmentReportingTables" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/Stock-basedCompensationTables" xlink:href="nthi-20250331.xsd#Stock-basedCompensationTables" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/DescriptionOfBusinessAndLiquidityDetailsNarrative" xlink:href="nthi-20250331.xsd#DescriptionOfBusinessAndLiquidityDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:href="nthi-20250331.xsd#BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/RelatedPartyTransactionsDetailsNarrative" xlink:href="nthi-20250331.xsd#RelatedPartyTransactionsDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/RelatedPartyLoansPayableDetails" xlink:href="nthi-20250331.xsd#RelatedPartyLoansPayableDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/RelatedPartyLoansPayableDetailsNarrative" xlink:href="nthi-20250331.xsd#RelatedPartyLoansPayableDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/LeasesDetailsNarrative" xlink:href="nthi-20250331.xsd#LeasesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/CommonAndPreferredStockDetails" xlink:href="nthi-20250331.xsd#CommonAndPreferredStockDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/CommonAndPreferredStockDetailsNarrative" xlink:href="nthi-20250331.xsd#CommonAndPreferredStockDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/SegmentReportingDetails" xlink:href="nthi-20250331.xsd#SegmentReportingDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/Stock-basedCompensationDetails" xlink:href="nthi-20250331.xsd#Stock-basedCompensationDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/Stock-basedCompensationDetailsNarrative" xlink:href="nthi-20250331.xsd#Stock-basedCompensationDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/CommitmentsAndContingenciesDetailsNarrative" xlink:href="nthi-20250331.xsd#CommitmentsAndContingenciesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://NTHI/role/SubsequentEventsDetailsNarrative" xlink:href="nthi-20250331.xsd#SubsequentEventsDetailsNarrative" xlink:type="simple" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/Cover" xlink:title="00000001 - Document - Cover" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/BalanceSheets" xlink:title="00000002 - Statement - Condensed Consolidated Balance Sheets (Unaudited)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaapAssetsCurrent" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaapCashAndCashEquivalentsAtCarryingValue" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapCashAndCashEquivalentsAtCarryingValue" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DeferredCostsCurrent" xlink:label="loc_us-gaapDeferredCostsCurrent" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapDeferredCostsCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_DebtIssuanceCostsCurrent" xlink:label="loc_nthiDebtIssuanceCostsCurrent" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_nthiDebtIssuanceCostsCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaapPrepaidExpenseAndOtherAssetsCurrent" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssetsCurrent" xlink:to="loc_us-gaapPrepaidExpenseAndOtherAssetsCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Assets" xlink:label="loc_us-gaapAssets" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssets" xlink:to="loc_us-gaapAssetsCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_DebtIssuanceCostsNetOfNonCurrent" xlink:label="loc_nthiDebtIssuanceCostsNetOfNonCurrent" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssets" xlink:to="loc_nthiDebtIssuanceCostsNetOfNonCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_DeferredCostsNonCurrent" xlink:label="loc_nthiDeferredCostsNonCurrent" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapAssets" xlink:to="loc_nthiDeferredCostsNonCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaapLiabilitiesCurrent" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccountsPayableCurrent" xlink:label="loc_us-gaapAccountsPayableCurrent" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_us-gaapAccountsPayableCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_AccountsPayableRelatedParties" xlink:label="loc_nthiAccountsPayableRelatedParties" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_nthiAccountsPayableRelatedParties" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_AccruedAdvisoryFeeRelatedParty" xlink:label="loc_nthiAccruedAdvisoryFeeRelatedParty" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_nthiAccruedAdvisoryFeeRelatedParty" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_LitigationSettlementPayable" xlink:label="loc_nthiLitigationSettlementPayable" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_nthiLitigationSettlementPayable" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaapEmployeeRelatedLiabilitiesCurrent" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesCurrent" xlink:to="loc_us-gaapEmployeeRelatedLiabilitiesCurrent" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PreferredStockValue" xlink:label="loc_us-gaapPreferredStockValue" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapPreferredStockValue" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaapCommonStockValue" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapCommonStockValue" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:label="loc_us-gaapAdditionalPaidInCapitalCommonStock" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapAdditionalPaidInCapitalCommonStock" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaapRetainedEarningsAccumulatedDeficit" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapStockholdersEquity" xlink:to="loc_us-gaapRetainedEarningsAccumulatedDeficit" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquity" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquity" xlink:to="loc_us-gaapLiabilitiesCurrent" xlink:type="arc" weight="1" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquity" xlink:to="loc_us-gaapStockholdersEquity" xlink:type="arc" weight="1" />
    </link:calculationLink>
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/BalanceSheetsParenthetical" xlink:title="00000003 - Statement - Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/StatementsOfOperations" xlink:title="00000004 - Statement - Condensed Consolidated Statements of Operations (Unaudited)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaapOperatingExpenses" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaapResearchAndDevelopmentExpense" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapResearchAndDevelopmentExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LegalFees" xlink:label="loc_us-gaapLegalFees" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapLegalFees" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaapGeneralAndAdministrativeExpense" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapGeneralAndAdministrativeExpense" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaapShareBasedCompensation" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_us-gaapShareBasedCompensation" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_AdvisoryFees" xlink:label="loc_nthiAdvisoryFees" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingExpenses" xlink:to="loc_nthiAdvisoryFees" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues" xlink:label="loc_us-gaapRevenues" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingIncomeLoss" xlink:to="loc_us-gaapRevenues" xlink:type="arc" weight="1" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapOperatingIncomeLoss" xlink:to="loc_us-gaapOperatingExpenses" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetIncomeLoss" xlink:to="loc_us-gaapOperatingIncomeLoss" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InvestmentIncomeInterest" xlink:label="loc_us-gaapInvestmentIncomeInterest" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetIncomeLoss" xlink:to="loc_us-gaapInvestmentIncomeInterest" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="loc_us-gaapAmortizationOfFinancingCosts" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetIncomeLoss" xlink:to="loc_us-gaapAmortizationOfFinancingCosts" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaapInterestExpense" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetIncomeLoss" xlink:to="loc_us-gaapInterestExpense" xlink:type="arc" weight="-1" />
    </link:calculationLink>
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/StatementsOfChangesInShareholdersDeficitUnaudited" xlink:title="00000005 - Statement - Condensed Consolidated Statements of Changes in Shareholders&apos; Deficit (Unaudited" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/StatementsOfCashFlows" xlink:title="00000006 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaapProfitLoss" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapProfitLoss" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_IncreaseInBridgeLoanExpensesPaidByBridgeLoanProviderOnBehalfOfCompany" xlink:label="loc_nthiIncreaseInBridgeLoanExpensesPaidByBridgeLoanProviderOnBehalfOfCompany" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_nthiIncreaseInBridgeLoanExpensesPaidByBridgeLoanProviderOnBehalfOfCompany" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_AccretionOfOriginalIssueDiscountOnBridgeLoansRelatedParty" xlink:label="loc_nthiAccretionOfOriginalIssueDiscountOnBridgeLoansRelatedParty" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_nthiAccretionOfOriginalIssueDiscountOnBridgeLoansRelatedParty" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaapShareBasedCompensation" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapShareBasedCompensation" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="loc_us-gaapAmortizationOfFinancingCostsAndDiscounts" />
      <link:calculationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapAmortizationOfFinancingCostsAndDiscounts" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInPrepaidExpense" xlink:label="loc_us-gaapIncreaseDecreaseInPrepaidExpense" />
      <link:calculationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInPrepaidExpense" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInDeferredCompensation" xlink:label="loc_us-gaapIncreaseDecreaseInDeferredCompensation" />
      <link:calculationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInDeferredCompensation" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_IncreaseDecreaseInAccruedAdvisoryFee" xlink:label="loc_nthiIncreaseDecreaseInAccruedAdvisoryFee" />
      <link:calculationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_nthiIncreaseDecreaseInAccruedAdvisoryFee" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="loc_us-gaapIncreaseDecreaseInAccountsPayableAndAccruedLiabilities" />
      <link:calculationArc order="9" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:to="loc_us-gaapIncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:label="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_us-gaapProceedsFromIssuanceOrSaleOfEquity" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromRelatedPartyDebt" xlink:label="loc_us-gaapProceedsFromRelatedPartyDebt" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_us-gaapProceedsFromRelatedPartyDebt" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfRelatedPartyDebt" xlink:label="loc_us-gaapRepaymentsOfRelatedPartyDebt" />
      <link:calculationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_us-gaapRepaymentsOfRelatedPartyDebt" xlink:type="arc" weight="-1" />
      <link:loc xlink:type="locator" xlink:href="nthi-20250331.xsd#nthi_DeferredOfferingCostss" xlink:label="loc_nthiDeferredOfferingCostss" />
      <link:calculationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:to="loc_nthiDeferredOfferingCostss" xlink:type="arc" weight="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" xlink:label="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" />
      <link:calculationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" xlink:to="loc_us-gaapNetCashProvidedByUsedInOperatingActivities" xlink:type="arc" weight="1" />
      <link:calculationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/summation-item" xlink:from="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" xlink:to="loc_us-gaapNetCashProvidedByUsedInFinancingActivities" xlink:type="arc" weight="1" />
    </link:calculationLink>
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/DescriptionOfBusinessAndLiquidity" xlink:title="999012 - Disclosure - Description of Business and Liquidity" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/BasisOfPresentationAndSummaryOfSignificantAccountingPolicies" xlink:title="999013 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/RelatedPartyTransactions" xlink:title="999014 - Disclosure - Related party transactions" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/RelatedPartyLoansPayable" xlink:title="999015 - Disclosure - Related Party Loans Payable" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/Leases" xlink:title="999016 - Disclosure - Leases" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/CommonAndPreferredStock" xlink:title="999017 - Disclosure - Common and Preferred Stock" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/SegmentReporting" xlink:title="999018 - Disclosure - Segment Reporting" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/Stock-basedCompensation" xlink:title="999019 - Disclosure - Stock-Based Compensation" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/CommitmentsAndContingencies" xlink:title="999020 - Disclosure - Commitments and Contingencies" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/SubsequentEvents" xlink:title="999021 - Disclosure - Subsequent Events" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesPolicies" xlink:title="999022 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies (Policies)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/RelatedPartyLoansPayableTables" xlink:title="999023 - Disclosure - Related Party Loans Payable (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/CommonAndPreferredStockTables" xlink:title="999024 - Disclosure - Common and Preferred Stock (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/SegmentReportingTables" xlink:title="999025 - Disclosure - Segment Reporting (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/Stock-basedCompensationTables" xlink:title="999026 - Disclosure - Stock-Based Compensation (Tables)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/DescriptionOfBusinessAndLiquidityDetailsNarrative" xlink:title="999027 - Disclosure - Description of Business and Liquidity (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:title="999028 - Disclosure - Basis of Presentation and Summary of Significant Accounting Policies (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/RelatedPartyTransactionsDetailsNarrative" xlink:title="999029 - Disclosure - Related party transactions (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/RelatedPartyLoansPayableDetails" xlink:title="999030 - Disclosure - Related party loans payable (Details)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/RelatedPartyLoansPayableDetailsNarrative" xlink:title="999031 - Disclosure - Related Party Loans Payable (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/LeasesDetailsNarrative" xlink:title="999032 - Disclosure - Leases (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/CommonAndPreferredStockDetails" xlink:title="999033 - Disclosure - Common and preferred stock (Details)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/CommonAndPreferredStockDetailsNarrative" xlink:title="999034 - Disclosure - Common and Preferred Stock (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/SegmentReportingDetails" xlink:title="999035 - Disclosure - Segment reporting (Details)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/Stock-basedCompensationDetails" xlink:title="999036 - Disclosure - Stock-based compensation (Details)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/Stock-basedCompensationDetailsNarrative" xlink:title="999037 - Disclosure - Stock-Based Compensation (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/CommitmentsAndContingenciesDetailsNarrative" xlink:title="999038 - Disclosure - Commitments and Contingencies (Details Narrative)" />
    <link:calculationLink xlink:type="extended" xlink:role="http://NTHI/role/SubsequentEventsDetailsNarrative" xlink:title="999039 - Disclosure - Subsequent Events (Details Narrative)" />
</link:linkbase>
