Change 123 is a fun martial arts styled ecchi manga based around the idea of a heroine who not only possesses split personalities, but who changes bodies with those personalities and who’s combat prowess changes with each form. It is just a little reminiscent of Battle Vixens (aka Ikkitousen) (some split personality aspects, martial arts, nudity, graphic violence), except with a higher emphasis on comedy.
And of course with every personality change we get a body change too, meaning there are four unique bodies to get naked with.
Unlike some ecchi series that just throw boobs in your face, Change 123 strikes a nice balance between nudity and quality non-nude fanservice. A typical volume might only have five or six panels with nudity, but they do a good job of teasing the reader and building up anticipation so that even ho-hum nude panels have impact.
A fun read that I would recommend if you like martial arts ecchi manga.
Change 123 (4 volumes, ongoing)