Paradistar

While being chased by the Yakuza for his family's debt, Chiba Tamao runs into a man who wants to "eat him," named Kurotengu. Kurotengu ends up saving Chiba's life, and in the process it's revealed that Kuro is actually a "mononoke" (type of Japanese demon) called a Tengu. Now a "friend" of Kuro's has paid of Tamao's debt to the Yakuza, but to pay him back, Tamao needs to work with Kuro in a boy band, while at the same time risking himself to be "eaten" by mononoke.

(Source: ANN)