Based on Natsuhara Takeshi and Hamori Takashi's manga, the story centers on a legendary delinquent who got injured, then asks an errand boy who got bullied to be his body double.

Ijuuin Shou is the leader of the Grand Cross, a gang of delinquents with over a thousand members. Yamada Tatsuhito is a perennial errand boy with no presence in class who is the bottom of the school hierarchy. When Shou ends up hospitalized, he proposes that Tatsuhito take his place as his body double for a month while he recovers to prevent the gang falling into disarray. Tatsuhito, who goes from a life of being bullied to a life as a delinquent leader, struggles to get through each day without others finding out his true identity. Takahashi Fumiya takes on a dual role of both characters.—Drama-Otaku

Tatsuhito Yamada (Fumiya Takahashi) is a second year high school student. He stopped going to school due to bullying. His parents, who have no interest in Tatsuhito Yamada's well being, have traveled abroad for work. Tatsuhito Yamada is all alone and he lives by himself. One day, he happens to see Sho Ijuin (Fumiya Takahashi) get into a motorcycle accident. Sho Ijuin is the leader of the largest delinquent gang known as Grand Cross. Contrary to his slender physical appearance, he is a strong fighter who has never lost a one-on-one fight. Due to the motorcycle accident, Sho Ijuin is seriously injured. Sho Ijuin also sees Tatsuhito Yamada, who looks just like him. He gets Tatsuhito Yamada to act as his double, but will he be able to survive as a gang leader?—AsianWiki

Sho Ijuin, the legendary leader of the delinquent gang "Grand Cross" that commands over 1,000 delinquents, and Tatsuhito Yamada, a perennial lackey with no presence in his class, cross paths one day. When Sho swerves his bike to avoid Tatsuhito, who had darted into the road, he crashes and sustains serious injuries. These two polar opposites, the strongest and the weakest, discover they look remarkably alike and decide to swap lives one day. Tatsuhito, the perpetual bullied kid, finds himself living in a new world as Sho, the strongest delinquent, and taking on the role of the leader of "Grand Cross," navigating a life filled with constant fights and power struggles. Thus begins the ultimate mission impossible, where being exposed would spell the end. Can Tatsuhito, the eternal lackey and bullied kid, manage to survive the tough daily life of a delinquent, all while keeping his true identity a secret?—tv asahi PROGRAM GUIDE