Teacher at Shoka Sonjuku. Speaks politely. First person: I (polite). Kind, but occasionally terrifying. Gintoki -> Gintoki Takasugi -> Shinsuke Katsura -> Kotaro

Student at Shoka Sonjuku. Often falls asleep during class. Constantly getting a knuckle sandwich from Shoyo. Shoyo -> Shoyo Takasugi -> Takasugi Katsura -> Zura

Student at Shoka Sonjuku. A bit short-tempered. Occasionally gets a knuckle sandwich from Shoyo. Shoyo -> Shoyo-sensei Gintoki -> Gintoki, Perm-head Katsura -> Zura

Student at Shoka Sonjuku. Surprisingly serious. Very rarely gets a knuckle sandwich from Shoyo. Shoyo -> Shoyo-sensei Gintoki -> Gintoki Takasugi -> Takasugi