Sickness unto Love by Yuki Shasendo (Hardback)

More than 150 deaths across Japan have been connected to Blue Butterfly, a game that leads people to take their own lives. The organizer of this terrible “game” is Kei Yorikawa, a seemingly good-natured high school student. How did a girl like her become such a monster? This story is a look back at the boy who changed her fate—her childhood friend, and her first kill.