The demure Yuuki looks like a normal maid with a prim dress and professional housecleaning demeanor. However, when she's not dusting the cabinetry or polishing the appliances, Yuuki raises up the gun and defends her master from diminutive maid robots.

As the proper story begins, Yuuki greets her young master in front of his grandfather's villa on a bright and sunny day. Despite the cheerful hello, not all is well as robots who look like super-deformed interpretations of Yuuki have invaded the estate and are on the attack. To add to the drama, a sexy blonde maid has also arrived to kidnap the young master. That won't do. Armed with powerful firearms, Yuuki plays the part of bodyguard who shoots, snipes, and swings a sword to dispatch her foes.

The bulk of the game is made up of levels where Yuuki roams around a level and blasts away at her enemies with conventional weapons. There are also special levels where she plays the part of a sniper or a speed racer chasing enemies on the run. As stages are cleared and points awarded, weapons may be upgraded to higher levels of performance. Mini-games and new clothes may be unlocked as well.