Kotarou Kobayashi

This twelve-year-old middle school student harbors a deep affection for Misaki and is Hatoko's brother. He has endured repeated physical attacks from Tamayo since childhood. A strong sense of jealousy arises when he sees Ohjiro pursuing Misaki, leading him to attempt a challenging martial arts bout against Ohjiro. With a background in karate from his family's dojo, he shares his skills with Misaki in hopes of aiding Hikaru's victory.