Synopsis
Mahiru Shirota believes that keeping things simple is best and that anything troublesome should be avoided. But he also thinks it's troublesome to do nothing and later regret it—a philosophy that leads the fifteen-year-old to take in a stray cat he finds on his way home from school. He names the feline Kuro, unaware that this encounter will completely change his ordinary life. One day, Mahiru comes home to find a strange young man he has never seen before. In his panic, the uninvited guest gets exposed to sunlight and, to Mahiru's shock, turns into Kuro! After revealing himself as nothing more than a lazy vampire who just wants to stay indoors, Kuro promises to leave once night falls. But one mishap after another causes Mahiru to accidentally form a contract with his new freeloader, dragging him into a life-or-death struggle involving supernatural servants and bloodthirsty beings—anything but simple.