The basic story is that the main character is a mouse guy who secretly breaks into that mansion in search of the "legendary cheese". This cheese is supposed to have the power to enlarge him.
However he gets caught by the two cat maids working in there (and whose boss is a real masochistic BDSM type, for instance he dresses the maids in leather).
The entire game is about degradation of the main character and also the owner of the mansion.

[Edited from the forum Eka's portal]