Sōichirō Kuzuki

A well-built man with angular glasses and a conservative hairstyle, Kuzuki is a strict instructor in Rin's class. He primarily lectures on World History, though he holds classes in Ethics.

Personality
Kuzuki is well respected among staff and students, but he is widely regarded as austere and impersonal.

Skills
Unknown to most, he is actually a highly trained assassin who has no qualms about letting his servant Caster do whatever she wants, even if the actions are considered evil. He has been staying at Issei Ryoudou's place for three years. In the anime, he has Caster enhance the power of his fists.