Hida Kizuna may have the HHG ability, but he's far from exceptional. When his sister enrolls him in a defense school where busty girls wield HHG to battle interdimensional foes in risqué attire, Kizuna's combat skills fall short. However, his sister devises a unique strategy: encouraging the girls to engage in intimate encounters with Kizuna to boost their powers. Brace yourself for a school life overflowing with awkward moments and unexpected twists!