<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2025-02-27</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001598428</issuerCik>
        <issuerName>Metallus Inc.</issuerName>
        <issuerTradingSymbol>MTUS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001078448</rptOwnerCik>
            <rptOwnerName>ELLWOOD GROUP INVESTMENT CORP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1105 N. MARKET STREET</rptOwnerStreet1>
            <rptOwnerStreet2>PO BOX 8985, SUITE 1300</rptOwnerStreet2>
            <rptOwnerCity>WILMINGTON</rptOwnerCity>
            <rptOwnerState>DE</rptOwnerState>
            <rptOwnerZipCode>19810</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isTenPercentOwner>true</isTenPercentOwner>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002066599</rptOwnerCik>
            <rptOwnerName>Ellwood Group, Inc.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>600 COMMERCIAL AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>ELLWOOD CITY</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>16117</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isTenPercentOwner>true</isTenPercentOwner>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4285026</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On February 27, 2025, Metallus Inc. (the &quot;Issuer&quot;) filed its annual report on Form 10-K indicating that, due to share repurchases by the Issuer, the number of its outstanding Common Shares had been reduced to 42,116,424 shares as of February 17, 2025.  As a result of the reduction in the outstanding Common Shares, the reporting person and joint filer's aggregate beneficial ownership increased to over 10%.</footnote>
        <footnote id="F2">The Common Shares are owned directly by Ellwood Group Investment Corp. (&quot;EGIC&quot;).  EGIC's parent corporation, Ellwood Group, Inc. (&quot;EGI&quot;), is deemed to be the beneficial owner of the 4,285,026 Common Shares owned by EGIC. EGI's address is 600 Commercial Avenue, Ellwood City, PA 16117.</footnote>
        <footnote id="F3">The Articles of Incorporation of EGI provide that, in the election of directors, the holders of a majority of the outstanding shares of EGI's preferred stock, voting separately as a class, shall be entitled to elect a majority of the whole board of directors of EGI.  Anna Barensfeld, an executive officer of EGI, may be deemed to be a person controlling EGI by virtue of her position as the trustee of the David E. Barensfeld Ellwood Preferred Stock Trust (the &quot;Trust&quot;), which is the owner of 100% of the issued and outstanding shares of preferred stock of EGI.  Anna Barensfeld and Trust each disclaim beneficial ownership of any of the Issuer's securities to which this Form 3 relates for the purposes of Section 16 of the Securities Exchange Act of 1934, as amended, except to the extent of her or its pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>ELLWOOD GROUP INVESTMENT CORP.

By: /s/  Shariee Thalmann
Name:  Shariee Thalmann
Title:   Treasurer/Assistant Secretary</signatureName>
        <signatureDate>2025-05-02</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>ELLWOOD GROUP, INC.

By: /s/  Craig Bicehouse
Name: Craig Bicehouse
Title: VP of Legal/Secretary</signatureName>
        <signatureDate>2025-05-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
