The former "guardian" of Hekikuu high. He's been a slave to the previous guardian for most of his high school life, and he thought he could enjoy being the guardian in his last year of school, but he is forced to resign soon after meeting Kitano. He's the most delinquent-like of the group, skipping lessons to smoke and provoking fights. Although he usually gets beaten up by others (Koiso Ryoko, Takehisa, other delinquents), he isn't physically weak - he is big and has a strong punch. The fact he is constantly defeated lies in his mind - he is easily scared and has tendency to panic. He is also simple-minded enough to be manipulated.

Kuroda desperately tries to reserve a leftovers of his dignity by acting like a guardian before Ogisu and his sempais. Also he has one-sided crush on Ryoko.

Ooshita and Tokiyama are his two lackeys/friends. Both of them have rarely been referred to by their actual names. Koide, the class president's assistant calls it a "miracle" that he was able to obtain their full names. As the story progresses, they realize Kuroda's weakness (and strengths, rarely good, though), but they kept on being loyal to him.

Another piece of trivia from the author himself, Kuroda serves as a pivotal character at the very start of the series, when the author experienced a writer's block.