Dohoon can't find a reason to live. He hoped to get a fresh start at his new high school, but things are no different-the bullies make fun of his limp and no one wants to be his friend. Then one night, he runs into a classmate, Aji... Having seen something he shouldn't, the two make a deal: Aji will protect him for the time being, but when he turns 20, Dohoon will have to pay up.