The Wicked Prince and The Helpless Pup

Kohei Sakaki wants to have a girlfriend, but his childhood friend Hiroki Ohno, who's popular at school, always seems to get in the way. One day, Kohei is asked to housesit for the Ohnos and snoops around in Hiroki's room trying to find his weakness. He finds a suspicious-looking DVD with the title erased, plays it, and finds that it's images of men making love... He tries to blackmail Hiroki when he comes home, but things don't go as planned...

(Source: Renta!)