Iczelion

Iczelion, the final entry in the Icz series, is a departure from the previous storyline in most respects.

Throughout the galaxy, two villains destroy and pillage anything in their path. Their names are Cross and Chaos, and they are ready to invade their next target: Earth. The only defense against these warriors are the Iczelions, a fusion of young girls, and Iczels, sentient body armor. Nagisa is a typical high school girl who is about to become the next Iczelion against her will, to defend the planet and save the human race! But not if she has anything to say about it...

(Source: AniDB, edited)