Ryosuke is Kawasumi's classmate and closest friend. He has known him since elementary and is in the Karate club with him.
He mentioned having a fight with his mother once, but it is not very serious. He started karate in elementary and met Kawasumi there. Ryosuke first thought Kawasumi was mean, but after they became friends considers him a cool person.
Ryosuke has messy black hair until his neck. His expression is usually playful, friendly or surprised throughout the story. He has very small pupils which makes him look more like a joker character.
He is most often wearing his school uniform, but he is also seen wearing his Karate club uniform when practicing.
Ryosuke is often cheerful and happy, and very carefree and friendly. He enjoys seeing pretty girls as much as all the other boys in their school (aside from Kawasumi), but he approaches them in a more friendly manner. He can be serious as well, such as when he discovered that Kawasumi liked Suiren. He told him that he could tell him anything, and that they were friends.