Hiroshi returns to his family home following his father's death, where he reconnects with his sisters and forms an intimate bond with a mysterious girl named Ojo. However, he soon discovers that Ojo is actually a Grim Reaper who sacrificed half of her life to save him in the past. As his sister Chitose undergoes a critical surgery, Hiroshi must face the heartbreaking reality of Ojo's departure and search for a way to save the supernatural being who gave everything for his sake.