Jiburiru - The Devil Angel

One hot summer day, Naoto Kamino finally musters up the courage to reveal his true feelings for his crush, Rika Manabe. Unfortunately, at the same moment, a young boy named Asumo appears (though he refers to himself as "a private in the Army of Hell"). He plots to kidnap Rika and will stop at nothing to obtain her—but Rika has a little secret of her own: thanks to the angel Misty Mei, she can transform and obtain magical powers during sex...