It's been a year since Siesta died, Kimizuka goes about his daily life as a high school student. His classmate, Nagisa Natsunagi, approaches Kimizuka and asks him to find an unknown person nicknamed "X". Kimizuka enlists the help of police officer FÅ«bi Kase to fulfill Natsunagi's wish. Kase takes them to a maximum security prison and Kimizuka is reunited with "Bat" who once fought a deadly battle.