Yamanaka has short, thick eyebrows with narrow eyes and pupils. He has a short, rough brown hair that is spiked in the front. He wears his school uniform, a grey gakuran with a standing collar that is black with teal trim. He leaves last button of his jacket undone; sometimes, he unbuttons the entire jacket. He doesn't keep his shirt tucked in and he is seen walking around with his hands in his pockets.
Yamanaka takes advantage of people for selfish purposes and bullies others. He has no problems lying to or manipulating people, even offering them false promises like membership to the Moon Demon Company. However in contrast, he's a coward who tries to act intimidating. When a real danger presents itself, his bravado dissipates, and becomes an immobile, trembling mess.
Given all that, he still cares about his friends. He is willing to be throw his pride away to beg for help when they are in danger.
At some point of his life, he enrolled into Second Shibuya High School, where he became friends with Shishido and Yūji and started the rumor that he was offered to join the Moon Demon Company, in order to make others fear him.
Events of 2020
Second Shibuya Arc
Yamanaka is first seen knocking Yoichi Saotome to the ground. He kicks Yoichi around and asks him buy drinks for him and his friends until Yūichirō Hyakuya intervenes. He and his friends ask Yūichirō, what does he thinks he is doing and gets ready to fight him. However, when Shinoa Hīragi mentions that Yūichirō's punishment will be extended if he gets caught harming a civilian, Yamanaka and his group manage to injure him without a fight. Afterwards, Yoichi tells Yūichirō that he wanted to ask Yamanaka for a favor, by letting him join his group because he was offered a place on the famous Vampire Extermination Unit called the Moon Demon Company and wants to use his connection to be allowed admission retest to the Japanese Imperial Demon Army, which he failed the first time.
Suddenly, an explosion occurs and an emergency warning siren immediately activates and informs all students and school personnel, that a weakened vampire has escaped from a biological research lab and has entered one of their classrooms during this time. When Yūichirō fights the female vampire. He sees Yamanaka and tells him to get the injured student out of the classroom since he was in the army, but he confesses that he lied and is too scared to move at all. Fortunately, Yūichirō and Yoichi manage to fight the vampire. She takes Yūichirō through a window and lands outside, where she is exterminated by Lieutenant Colonel Guren Ichinose who has bought the actual Moon Demon Company.
Later, Yamanaka and Shishido chase down Yoichi, apologizing for picking on him after hearing he got into the Moon Demon Company. He asks Yūichirō and Yoichi to help his friend Yūji who entered the forbidden underground area found underneath the school, which is one of the army's class one restricted zones, and has yet to return. Shinoa tells them that Yūji wanted to test his strength. She also mentions he was probably arrested and may even be executed. However, it was revealed by Shinoa shortly after, when she told Yūichirō and Yochi that it's a underground temple that actually serves as a training ground for the Vampire Extermination Unit and those who undergone enough training can go there in without being possessed by a demon, which most likely happen to Yūji. They go to the underground temple to save him.
- "Stop what? You're makin' it sound like we're picking on you or something. But we're just asking a friend to buy us drinks, right? So what's with the attitude?"
- —Yamanaka to Yoichi. ("Humanity After the Fall")
- Satoshi 「聡」 is a Japaneses name that means "clear-thinking; quick-witted; wise."
- Yamanaka 「山中」 is a Japanese surname that means "in the middle of the mountain."