Five years ago, alien beings known as the "Kiseichuu'' invaded the world. With the species endangered, the Kiseichuu are determined to take over Earth through a deadly plan that would gradually wipe out the human race: take away humanity's sexual drive using various methods, letting them die out. In response to the Kiseichuus' scheme, the HxEros device was developed-a powerful weapon that only those with high levels of erotic energy can utilize at its maximum capacity. Retto Enjou, a high schooler harboring an immense hatred toward the Kiseichuu, joins a group of HxEros users to fight against them and protect humankind. With their gear reliant on erotic energy as a source of power, the team must work together to maintain high levels of libido to ensure their readiness for combat at any given time. Moreover, as he lives in a house full of lustful girls, Enjou should not expect a shortage of power anytime soon.