A genius con artist, Otowa No. 4, is a "chivalrous thief" who uses his exceptional and handsome looks as a weapon to rip off money from villains around the world. Otowa No. 4 is finally arrested, but he succeeds in escaping with Azabu No. 10 while being transported under police escort. The two men, who happened to take refuge in a grove of trees at a high school, Hikari Gakuen, strike a deal with its principal, Mizuki Kenichi, and end up working at the school. Otowa No. 4 becomes Hachisuka Goro, a new teacher who graduated from Tokyo University, and makes full use of his swindling techniques to conduct "hammer sessions" for problem students.