Mahiru Shirota firmly believes that simplicity is best and complications should be avoided at all costs. The notion that doing nothing only leads to later regret drives the 15‑year‑old to pick up a stray cat on his way home from school. He affectionately names the animal Kuro, unaware that this chance encounter will spark a profound shift in his ordinary days.
One afternoon Mahiru returns home to find something truly odd: a mysterious young man he has never seen before. His sudden alarm forces the unexpected visitor into sunlight, and to Mahiru"s astonishment he transforms into Kuro! The creature then confesses that he is a dormant vampire who will depart once night falls. Yet a series of mishaps forces Mahiru to accidentally bind himself with the freeloading stranger, pulling him into a perilous clash of otherworldly servants and blood‑thirsty foes that is far from simple.
