Seemingly ordinary schoolboy Yuta meets the Demon Princess Lucia who explains her plan to mate with him and produce an all-powerful demon child in order to revive the defunct Demon realm. This is possible because of his date and time of birth, which forms six sixes. Shortly after this meeting, his crush from the school art club, Rie, reveals that herself and fellow classmate El are in fact angels sent to watch over him and prevent this monstrous birth.
Despite refusing to make a child with her, Yuta strikes up a friendship with Lucia, but when she enrolls at his school, and in the art club, he knows that his peaceful days are over.
Later, a trip to the seaside for the art club proves to be anything but relaxing thanks to El's antics and something dangerous lurking in the sea's depths.
This volume collects the Princess Lucia pilot chapter, as well as chapters 1 through 3 and provides profiles for Yuta, Lucia, Rie & El.