Takuya Muramatsu is a student of Kunugigaoka Junior High School. He is assigned to Class 3-E, where he trains to become a professional assassin, with his teacher as the target. His partners are Ryōma Terasaka and Taiji Yoshida. Muramatsu is an inconsiderate individual, unmindful to the consequences of his actions. He is willing to resort to any means in order to escape contemptible circumstances. He collaborates with Ryōma Terasaka and Taiji Yoshida, and together they pressure others to act according to their bidding.