- First appearance: Battle 63 Age: 12 Type: Sei Type: Katsujin Ken Martial Arts: Jujutsu (Yamamoto Style) Yamamoto Naoki is the son and disciple of Yamamoto Taiki. He helped with Kenichi's training to overcome dirty tactics. Naoki uses a different style of Jujutsu but also incorporates tactics into his fighting, defeating Kenichi in their first match. He and Kenichi entered the Cave of Death. It is sometime for punishment or training. He said his father defeated a Tengu and seal him inside the cave but actually it was his father in disguise. He said that if he could hit the Tengu he could visit the city which is his dream. Later there's a second match and he lost because Kenichi trained himself to counter him. After he lost he and Kenichi become friends and someday fight again. In the extra shot he met a kappa but he thought its a city boy. He sometimes appears in flashbacks when mentioned as an opponent of Kenichi or as proof of different methods to train children or disciples into martial arts. Naoki was also sent to the middle school that Honoka attends as a first-year student. There, he finds his desk vandalized and himself bullied, but mistakes it for the school's norm and continues living normally. Upon recognizing it as bullying, Naoki is tempted to attack but resolves not to use his martial arts for the wrong end. When he finds those bullies being bullied by high school students, Naoki saves them with his Jujutsu, earning their gratitude and indirectly convincing them not to bully him anymore, though he finds it odd that his desk is clean the next day, believing that something was out of the norm.