It's not a formula that has been tried before, but it works pretty well. You play the part of Kinoko, a young lady in the employ of the TCTF, a government agency that cracks down on illegal activities in a futuristic Japan. Kinoko is a purple haired, hard hitting, ninja dynamo who, we come to find out, is a rather special individual for more reasons than her martial arts skills. The combination of ranged and up close and personal combat in Oni is the game's strength. Make no mistake, this is mostly a game about using your hands and feet however, since ammunition for the various weapons is very rare indeed.
Ammunition comes in a couple of flavors and each type fits in more than one weapon.
Kinoko can only carry one weapon at a time, she has to drop one to pick up another. Speaking of which, you have a vast number of combination moves at your disposal in the game. These are learned as you progress. These include spin punches, rolls to avoid hits, and a whole host of special attacks including a spin that knocks opponents down, running choke holds and other inventive martial arts moves. Not only can Kinoko use all sorts of moves, but her opponents can too.