Baito no Senpai ga TSkko ni Natta no de Loli Maid ni Shite Yashinaitai!

Shunichi has grown distrustful of others after his parents suddenly died.
He starts a new job at a convenience store, and comes under the wing of a kind guy there named Akiya.
But one day, a sex-change disease turns Akiya into a cute loli girl.

Akiya loses her job, and the protagonist decides to hire her as his personal live-in maid!
And so begins their dreamy sex life...

[From DLsite English]