Yasushi Tajiri, nicknamed "Colonel" or "Taisa," is the head butler of the Kuonji family mansion. His history in special forces operations left numerous scars across his entire body, typically hidden beneath his formal butler attire.

Tajiri perceives himself as exceptionally attractive and maintains a formal, disciplined demeanor in his duties. He trains new servants, implementing rigorous and demanding methods particularly with Ren Uesugi. Despite this strictness, he holds underlying respect for Ren's potential and demonstrates steadfast loyalty to the Kuonji household.

His behavior frequently features parodies of other anime series, especially Mobile Fighter G Gundam, serving as an intentional in-joke referencing shared voice actors. Tajiri's characterization incorporates ambiguous suggestions of homosexual tendencies, primarily utilized through yaoi-themed innuendos for comedic effect.