Alluring Secret : Black Vow

The novel adaption of HitoshizukuP's "Himitsu ~Kuro no Chikai~ Alluring Secret ~Black Vow~" is about Rin, a young angel who falls in love with a young human girl, Miku. However, their love is considered taboo because of their gender and race, and so, Rin makes a deal with the devil to be reborn as the human boy, Len...