Yuuka and Tsurugi Okkotsu carry a name that commands absolute respect and absolute fear. As the grandchildren of Yuuta Okkotsu and Maki Zenin, they possess a terrifying blend of Boundless Cursed Energy and Peak Heavenly Restriction. But their mission isn't just to exorcise; it’s to babysit. Paired with Maru, a three-eyed Simurian envoy, they must navigate a high school life where cultural exchange involves Special Grade curses and alien tech. Behind the smiles and school festivals, the siblings are uncovering a truth both Earth and the Naunax want buried: the Simurians didn't come to visit they came to survive.