Taiki is your average guy. He’s nineteen years old, in his first year of university, and he’s just starting to learn what it means to be an adult. During the summer vacation, Taiki goes to the countryside to stay with his grandparents alongside his siblings: the haughty, fashionable Chiharu; the tomboyish troublemaker Nene; and the sweet, shy Reza. Taiki wants to have a relaxing summer, but his hopes are dashed when Nene breaks into their grandfather’s study, which is strictly out of bounds. Inside his study, Nene finds a treasure trove of dusty old books, including a tome full of instructions on how to summon demons. Nene sets about this demonic summoning ritual at once, and calls upon a fearsome figure from the deepest, darkest depths of Hell… Who just so happens to be a cute girl with pink hair and an impressive bust?! Now Taiki’s in a real pinch. Not only does he have to look after his siblings, but he also has his demonic guest, Elisabeth, to worry about – and she’s completely besotted with him! What in the world is Taiki going to do now?!