Yotsuyu Yagiyama

Yotsuyu Yagiyama is an ambitious and ruthless Rock Human. Rock humans are a silicon-based lifeform similar to humans and living alongside them, who possess unnatural abilities such as hardening their skin into stone or endure extreme temperatures; they also can enter a state of hybernation, during which their bodily functions slow to a crawl and they sleep for an extended periods of time. Rock humans possess a very low to none social drive, avoiding connections that don't benefit them directly, and lacking empathy or attachment towards others.

Yotsuyu is a 28 year old architect, although he is secretive of his work and his origins. He is a loner, who shows himself to be eloquent, perceptive, confident and intelligent, both in battle and in his line of work. He shows himself to be rather confident in himself and his abilities. He's cold, distant, arrogant and doesn't trust people, avoiding unnecessary conversation, but he enjoys commenting on things that make him curious, or seem interesting or beautiful. He has an exquisite taste, and shows an appreciation of the natural beauty, making observations of the things in his surroundings. Yotsuyu is a bit strange and even weird when it comes to speech, often sounding distant and talking about things that seem unrelated to the topic.

Yotsuyu doesn't hesitate to use violence to get what he needs, if it comes to that. However, he can be sympathetic to others who have been betrayed, such as his friend Aisho Dainenjiyama, whom he values to some extent, while still not putting this relationship above his goals.

Above all, Yotsuyu desires social status.

Yotsuyu is ruthless and calculating, as he repeatedly takes underhanded measures to fulfill his goals. He is the type of person who will attack innocent people in order to show he is serious about his threats. He is a ruthless person, as well as showing clear signs of sociopathy, due to his nature as a Rock human and his ambitions which he puts above all else.

He is an architect who worked on the Higashikata Family mansion and the baseball stadium where Aisho Dainenjiyama works.