Kaito does not have an official last name. Fans have given him the fanmade last name "Shion" for a currently unknown reason, it's presumed fans gave Kaito a last name to match the later Crypton releases who have their own set of official last names that relate to their character.
This fan given last name has no official holding.
- This page is a soft redirect.
- See - What information can be given about the Shion family?