Finder Series 3: Finder No Sekiyoku (You're My Love Prize of One Wing) By Ayano Yamane, in Japanese

Fei Long, the Chinese crime lord, goes to Japan hoping to lure Akihito, a freelance photographer, into his twisted web of conspiracy and sex. But when his friends fall prey to Fei Long's diabolical schemes, Akihito has only one person he can turn for help; the person he despises more than anyone else - the Yakuza boss Asami, who once made Akihito his sex slave. How will Asami respond to Akihito? Will he help him? And if he does, what is it going to cost him? What kind of new humiliations are in store for him?