One Day My Love Will Blossom.

Hajime Mamiya decides to quit the yakuza business after the death of his boss. When riding on a bus, he meets Sho Kosaka, a college student who is close to his boyfriend. One day when Mamiya couldn't forget Kosaka's longing face towards his boyfriend, he reunites with him, who apparently works part-time at 'Deriheru'. Mamiya doesn't know how it feels to love someone, but he learns of Kosaka's devotion to selling his body, and decides to buy all his time so that he doesn't have to take other customers. A pure story of a slowly falling in love with a former yakuza who doesn't know love and a college student who wants to love and be loved! (Source: Gentosha, translated)