Love or Pride Manga
As the son of a yakuza, Taiki was investigating a shop when he accidentally stumbled upon a young man giving the assistant manager a blowjob. The next day, he saw that young man, Yukiya, again. Yukiya begged Taiki not to tell anyone about what he saw and Taiki jokingly asked for Yukiya's body as payment. But he discovers unexpectedly that he's Yukiya's first man! Included in this manga is a sweet extra about Taiki and Yukiya when they've grown up. Written after Bitter Sweet CafÃ©, but takes place chronologically approximately 20 years before it.