If the main character had ever gone berserk in an anime, it would most likely be Tokyo Ghoul. The main character, Kim Mu-yan, was an ordinary high school student. However, after being infected, his body began to mutate and he became extremely powerful in combat and berserk. In this story, Kim Mook Yan constantly fought with all kinds of monsters to protect himself and the people around him. He had to face the challenges brought by the power of berserk.