Shota Yamazaki (山崎翔太, Yamazaki Shōta) is a high school student and the only son of an elite family. His hobby of killing cats earns him a visit from the avengers.
Shota is described as tall and eloquent. His handsome features, combined with his family's obvious wealth, make him popular at school. He is seen wearing a school uniform with a standing collar. In the anime, he has multiple ear piercings.
At a glance, Shota seems to be a model high school student. He is polite, excels in athletics and academics, and has many friends at school. His parents travel for work, leaving him alone for days at a time, however, and he shows a sadistic side behind closed doors. In his free time, he takes pleasure in torturing cats he picks up off the street, and he uploads photos and videos of the torture online.
Prior to the start of the story, Shota captured a cat off the street, tortured and killed it, and uploaded photos of the cat online. The cat's owner, Miura, was distraught and contacted the avengers.
Mayor Harada Scandal Arc
Jiro and Misaki Tanaka visit Shota's house under the pretense of delivering cakes to their new neighbors. When Shota answers the door, Misaki acts like a child, running inside without invitation to marvel at the large house. From studying the layout of the house beforehand, she runs to the bathroom and finds a cat alongside hammers, knives, and other tools. Jiro questions Shota about the cat and explains Hammurabi's Code and the existence of avengers. When Shota understands that their visit was premeditated and realizes what this means for him, he passes out.
Jiro and Misaki put Shota in the backseat of their van and go to pick up Jun Murase, unknowingly capturing Kazuki Saitoh instead. After failing to find Tatsuya Yamashiro and Masaki Yoshida, Jiro drops Misaki and her new cat off and brings his victims to a warehouse near Hakata Bay where the torturer José Martínez has been waiting.
Planning to exact revenge on both of the bound men, Jiro starts with Shota. He describes how Shota tortured and killed the cat, and Martínez begins punching Shota in the face, arms, and torso. He alternates between hitting the boy and taking hour-long breaks until Jiro is ready to move on. Shota wets himself before Martínez crushes his eyes, and when he becomes able to talk through the pain, he apologizes and begs for forgiveness on camera. When the torturers are content that he understands the suffering of his victims, Shota is decapitated. The video of his death is uploaded to the same website where he had uploaded his torture videos, and at some point, a handwritten note reading "I'm leaving home. Don't look for me," is left in his home, discouraging the police from becoming involved in his disappearance.
After his body is brought to Saeki's Cosmetic Surgery Clinic for disposal, Zenji Banba offers to buy it, and Jiro and Shinichi Saeki dress up Shota's head to look like Banba's. The Niwaka Samurai later presents the severed head to Zhang and his subordinates to prove that Banba is dead. In the anime, Shota's ear piercings tip Lin off to the Niwaka Samurai's true identity.
Ten months after his disappearance, the private detectives hired by his mother Mieko Yamazaki have turned up no leads as to his whereabouts, and his mother has been abusing cigarettes and alcohol in order to cope. His grandfather, Kunio Yamazaki, discovers evidence of his torture and, believing him to be dead, asks Sanjou of the Mutagawa Group to find Shota's murderer.
Sanjou finds the video of Shota's torture and death online and watches it with his subordinates. They determine that Shota was killed by an avenger and take steps to contact one, planning to force the avenger to confess before handing him over to the Yamazaki family.