First, sign into Cygames ID through your browser, then check the Linkable Games section on My Page. If "Unlinked" is displaying as the status, then try the following steps.

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Confirm that the (email or third-party) account you've used to sign in to Cygames ID matches the one you used when linking your game account to Cygames ID. You can do this by selecting Account Information from My Page on Cygames ID.

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[If the Accounts Don't Match]

If the Cygames ID used to link your game does not match the account you're currently signed in with, sign in to the account linked to your game and confirm your account's status.

Note: This answer is for the English version of Umamusume: Pretty Derby.

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