When you create an account, you are automatically assigned a unique string of characters which will be your pixiv ID.
You can change your pixiv ID once per account after signing up.
Become a pixiv Premium user to change your ID as many times as you like.
※ Once you change it, you cannot revert to the previous pixiv ID.
※ After changing your pixiv ID, you won't be able to change it again for 30 days.
Please enter a character string of your choice that consists only of 1-byte alphanumeric characters, hyphen "–" and/or underscore "_" in the entry field of pixiv ID. However, you cannot register using the same character string as an already existing pixiv ID. If string is already in use and registration is not possible then try again with a different character string.