Primary

• Toshiki Kai Childhood friend of Ren Suzugamori
• Toshiki Kai Childhood friend of Tetsu Shinjyou
• Toshiki Kai Best friend of Aichi Sendou

Extended

• Aichi Sendou Older Brother of Emi Sendou
• Aichi Sendou Friend of Toshiki Kai
• Ren Suzugamori Best friend of Tetsu Shinjyou
• Ren Suzugamori Friend of Asaka Narumi
• Ren Suzugamori Childhood friend of Toshiki Kai
• Ren Suzugamori Friend of Aichi Sendou
• Tetsu Shinjyou Best friend of Ren Suzugamori
• Tetsu Shinjyou Friend of Asaka Narumi
• Tetsu Shinjyou Childhood friend of Toshiki Kai