"Can't we all just live together?" It would be nice, but for the twin brothers Il-do and Yi-do, it's just a wishful thought. Born under a cursed fate due to their parents' original sin, one must die for the other to live. To avoid this, they have deliberately cut off contact. However, when Yi-do, who works for a gang, gets stabbed, Il-do somehow hears about it and rushes to donate blood, saving his brother's life. But instead of gratitude, Yi-do attacks him the moment he sees him.

Youngdo’s father, a notorious serial killer, was executed. Youngdo wants to let go of what he remembers about his father but he doesn’t know how to do so, and he ends up releasing his anger through violence.