The son of the boss of the "13 Bullets" yakuza clan, Reigai Yurei, also known as Vector, is preparing for his test mission, the success of which will determine whether he will take his father's place or not. However, during the quite successful progress of the mission, he is killed by an unknown “immortal soldier”. After his death, Reigai was sent to the lowest floors of the underworld. From local legends, he learns that there was a man who also ended up here and successfully got back to the world of people. Now the clan heir has only one directive: find and kill his killer.