GitHub Username Policy - GitHub Docs

GitHub account names are available on a first-come, first-served basis, and are intended for immediate and active use. What if the username I want is already taken? Keep in mind that not all activity on GitHub is publicly visible; accounts with no visible activity may be in active use. If the username you want has already been claimed, consider other names or unique variations. Using a number, hyp

[nilab]

Name Squatting Policy - User Documentation

[iwadon]

@masuidrive 中の人が見つかるまでに時間がかかるようでしたらGitHubのスタッフに連絡するのも手だと思います。