In this modern society, people are mandated from childhood to form pairs with a destined partner and spend their lives together. Destined pairs basically live in the same room.

Guest and Dan have received elite education since childhood, raised as professional assassins. Through grueling training in a harsh environment where they literally spat blood, Dan eventually became pathologically dependent on Guest.

Now, Dan's secret feelings for Guest have become so twisted that he is about to take drastic measures.