Ten is a high school boy who wants nothing more than an ordinary, peaceful life. That simple wish is complicated by the fact that his entire family are monsters, and he himself is half-human and half-monster. When a portal is torn open between the monster world and the human world, a horde of monsters floods into the human realm. Ten and his brothers, known as the Tatsugashira siblings, are given an extraordinary mission: hunt down and drive back the invading monsters. The reward for success is the granting of a single wish. For Ten, that wish would finally be the normal life he has always dreamed of. As the siblings battle the monsters, a parallel conflict unfolds between two estranged friends from the previous generation, one that traces back to a village where the true secret of what the family has been protecting is rooted. Ten must grapple with the choice of whether to sacrifice his human side in order to protect his monster family and unlock his own strength, all while deciding what a normal life truly means.