Kizu Darake no Tenshi-tachi ~Maid Kenshuusei~

At the mansion of shadow cardinal of Japan politics four maids are being trained. But after two weeks of training the owner gets to a hospital. Mansion secretary has to employ protagonist as a temporary instructor. One night some drug is released in the rose garden, and one maid goes missing afterwards. At the same time remaining three maids get insulted by a figure in the mask of a demon. Chaos arises at the mansion, but the missing maid returns. She conveys the truth that has been revealed to her...

[From vndbreview]