Yuina Hatori is a plain girl who insists on never being noticed and never causing trouble. One day, however, an 'angel', who is actually a sort of bioroid called an Emulate, Seraph, falls out of the sky and nearly into her arms. Beginning here is a sweet relationship between Yuina and Seraph, along with jealousy and anger as Yuina's old friend and her 'Emulate', Lucifer. Yuina learns that she is not meaningless, and slowly falls in love with Seraph amid fights with Lucifer.
