- Official name:山下一夫
- English name:Kazuo Yamashita
- Chinese name:山下一夫
- Other names:やました かずお / 一夫大帝
- Gender:Male
- Birthdate:Mar 8
- Height:167cm
- Weight:64kg
- 喜好的东西:观赏格斗技,平稳的生活
- 座右铭:塞翁失马 焉知非福
- 所属:山下商事
『Kazuo Yamashita』
Yamashita Kazuo starts as a timid, average person who is pushed around by the manager in his company "Nobi Publishing" and by other people in general. However, after meeting Ouma and being exposed to blood lust and other fighters in the Kengan world, he started to lose his fear of ordinary people such as his manager and even to thugs who threaten to kill him. During the Kengan Annihilation Tournament, Yamashita becomes much more brave and respected.
Yamashita Kazuo has a wife and two sons. His wife left him ten years before the story began. He had been employed at Nogi Publishing for 34 years. He enjoys watching martial arts and living a peaceful life. Yamshita's motto is, "Good can come out of misfortune."
By the end of Kengan Ashura, Kazuo becomes the CEO of Yamashita Trading Co.In Kengan Omega, Kazuo's company takes a new role of taking in freelance fighters under the order of Hideki Nogi, the chairman of the Kengan Asociation.