A member of The Front of Armament's 7th Generation.
Yamaguchi challenged Takumi after realizing he was the strongest man at his school. He lost the fight but gain a new found respect for his future leader .
Yamaguchi is very charismatic and eager to fight any and all opponents of the Front. He is not always successful in his bouts with more known losses than wins.
- Zenjirou vs. Takumi - Lost 
- Zenjirou, Ozaki, Yaita, Takumi, Katsuhiro, Sakota vs. Team Tahara - Won 
- Zenjirou vs. Masaoka Kenichirou - Won 
- Zenjirou vs. Zakuro Aki - Lost