Tachibana Ryusei

He works as a math teacher at the protagonist's school.
He's a quick thinker who can complete any task speedily.
With his cool personality he has good efficiency in making plans that further his goals.
He's weak when it comes to things that he doesn't expect.
He has a complex about his childlike face and unruly hair.
He's Tomu's big brother and often dotes on him.
His flower is the Marguerite.