He is a short man with slightly disheveled hair and wears glasses. He usually wears the standard CCG uniform, or a smart suit.
So far his personality is unknown.
At the auction, he and his squad are separated from Mado Squad and are assigned to stop the ghoul Naki, who is accompanied by Miza.
- Isai was modeled after one of the 20 winners among the applicants to the ghoul investigator recruitment campaign. He is associated with "hot and cold, heating and cooling" (冷熱, reinetsu) in the operation reports attached to the chapters.