Yuta is an ordinary boy whose precise birth moment marks him as the ideal father for a uniquely powerful child, which is why Lucia, a princess from the demon realm, sets out to win him over and bear that child. Standing in her way are two angels, Rie and Eru, sent to make sure no such child is ever born. Caught between the demon princess pursuing him and the angels guarding him, Yuta finds his everyday life overrun by the supernatural.