YaoiLover's manga / #Demon King(2)

The demon lord from this story is almost identical to the one from "Demon Wants to Hug" manga. That story is not a yaoi, so this one kinda fills that void. Im curious how the relationship will progress.

The demon king has exhausted his wealth, after a war with the humans. He is no longer receiving tributes from subjects, and couldn't afford to pay his soldiers. Now, with only two, loyal subjects/servants, the demon king needs money! He decides to look for work in the human world, but is not suited for most jobs. He stumbles upon a job as a sex worker, servicing knights. His new boss, "Manager", is training the demon king on performing various sexual acts, to earn more money. During the course of training, Manager realizes the demon king is sexually inexperienced, despite being a 350yo demon king!