we could have a random ability of being born as an experiment of orochimaru like kyuubi and seal and it has a stage 1 where its just one arm and your neck and face, next stage is that your body is fish like but you still look a little human next stage you are red eyed and are pretty much completely a fish that stands
it gives you a big taijutsu bonus while active andyou can spit water in large streams to do damage. also gives you the ability to go underwater(pretty much going invisible) and you get a special summon of water boss which covers where you are in water and you have the ability to trap them if they are near you (like shar freeze) in a bubble of water.