Hot Limit (2006)

Blurb:
Directionless Kazuma is so indifferent about getting a college education that he devotes himself to work—“work” being a series of trivial jobs meant to kill time as much as pay the bills. During his nighttime bar shift, Kazuma meets “Maya”, a seductive partyer with an overactive libido and an attitude way bigger than his petite size. When Kazuma accepts a daytime servant’s job at a local mansion, he discovers “Shinya”, a well-mannered honors student who could be Maya’s physical twin. Is there some connection between the two, or is Kazuma’s mind only playing tricks on him?

Source: www.anisearch.com/manga/4902