Primary

• Leon Soryu Friend of Aichi Sendou
• Leon Soryu Friend of Toshiki Kai

Extended

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