Primary

• Ken Murata Best friend of Yuuri Shibuya
• Ken Murata Reincarnation of Double Black Great Sage

Extended

• Yuuri Shibuya Best friend of Ken Murata
• Yuuri Shibuya Son of Miko Shibuya
• Yuuri Shibuya Engaged to Wolfram von Bielefeld
• Yuuri Shibuya Son of Shoma Shibuya
• Yuuri Shibuya Younger Brother of Shori Shibuya