Kiiko Sasaki stands as the sole female operative in the Yamainu Squad, where she specializes in firearms deployment. At 24 years old, she measures 160 cm tall and weighs 50 kg, with blood type A. Among her Yamainu comrades, she carries the moniker "Princess Sasaki." Her past intertwines deeply with Sousei and Tenka, forged through a shared childhood spent growing up together.