A short, fat, and lonely boy who is a habitual liar. When someone tries to steal Nagatsuka's bike, Ishida offers his to be taken instead. Nagatsuka sees this act of kindness as a unbreakable act of friendship and swiftly becomes Ishida's self-proclaimed best friend and starts to idolize Ishida. He is shown to be quite obsessive and protective of Ishida and often dislikes him befriending other people. However, Nagatsuka is also supportive of Ishida and often offers advice. He has plans to become a millionaire, so is willing to hand out money to friends and is keen to become a film director—entering himself and Ishida into a film competition. It is shown both Ueno and Kawai find Nagatsuka repulsive, while Ishida is uncomfortable that Nagatsuka is so willing to take his side when he knows so little about him. Though his film proves to be a failure, this only made Nagatsuka resolved to take up film studies as his college subject.