Full name: Kagaya Mukurone. The biological father of Guest and the head of the Kyuryukai crime syndicate. He dotes on his son obsessively. Immediately after the birth, he banished the child's mother; she still pleads for her son's return, but he ignores her completely. Usually, he is smiling and soft-spoken, using the beautiful, archaic courtesan dialect (Kuruwa-kotoba) that makes him almost mistakable for a woman. However, once he dons his mask as the Boss, he becomes cold and ruthless. He is a handsome man with long, raven-black hair and crimson eyes. He used to love his tobacco pipe but has cut back since his son was born. He fights by manipulating threads. His obsession and love for his son are bordering on abnormal. He usually wears a casual kimono (kinagashi). He has a dragon tattoo on his back. He calls Guest 'Bo' (Little One).

Full name: Akito Yukimura. An executive of the Kyuryukai and the Underboss's Assistant. He is Kagaya's right-hand man. He is always smiling, but his true nature is pure ferocity. While he is usually calm, collected, and polite in a somewhat aloof way, he becomes uncontrollably violent once angered. He listens well to Kagaya and Guest, whom he respects and loves above all else. He always looks down on others slightly. He speaks with a Kyoto accent. He has a snake tattoo on his arm. He mostly fights with his fists, but uses a katana in emergencies. He calls Guest 'Waka' (Young Master). He is a handsome man with golden hair tied up high and golden eyes, wearing a casual kimono.

Full name: Rinne Kudo. An executive of the Kyuryukai and the caretaker for the Young Master. He is Kagaya's left-hand man. He is blunt and unsociable, but he gets his work done. He has a foul mouth, a sharp glare, and a bad attitude. He is a junior member within the Kyuryukai and generally addresses others with '-san'. Though usually calm and collected, his IQ drops the moment it concerns his beloved Kagaya or Guest. He usually uses his fists but uses a gun in emergencies. He calls Guest 'Waka' (Young Master). He has a tiger tattoo on his back. He is a beautiful young man with short, raven-black hair and blue eyes.