Tatsuyoshi Kasai  

, 葛西辰由

Tatsuyoshi is a member of the Sonozaki family who resembles a secret agent. Although he was previously more active, he now serves as Shions caretaker. Despite this, he maintains connections with both Teppei and Rina, being privy to their lifestyles and harassment tactics. In Matsuribayashi-hen, Tatsuyoshi exhibits remarkable strength and combat skills while leading a raid on the Irie Clinic, frequently subduing Yamainu members.