Asahina was a police officer with extraordinary skills and cautious actions, but he was frustrated in an incident and had to leave the police station. Since then, he has been engaged in security work. One day, Asahina was assigned to the most difficult and dangerous "Guard No. 4" mission, and Ishimaru was designated as his partner. Ishimaru used to run a company, and his cautiousness continued to his security work, and he was called a "coward". They will protect various important people: blind people, women participating in elections, gang bosses...