Matsumoto Makoto

Uno and Yuuna are altered humans by ARCA. With a kiss, they can fuse and become , ARCA's strongest. Although they don't like fusing, they make a deal with ARCA to pay their debts. They fight , humans that have absorbed a "Heart" and transform into monsters.

A box that grants three wishes might seem like a dream come true. At least that's what Keita thought, but inside the box he finds a girl. And this girl is no genie–Maki's a devil princess, and she's come to take Keita's soul! But she can only take his soul after he makes his third wish. So, as a sheltered demon with little knowledge of how to be evil, Maki must rely on her trusty guidebook to teach herself the ways of the nefarious arts and trick Keita into using up his wishes. Until then, Maki's going to live with Keita until he can't stand living anymore.