Arisa☆Good Luck(1999)

Arisa, a 16-year-old high school girl, accidentally has an extreme fighting suit that her brother invented implanted in her body. It's a slightly embarrassing suit that makes her emit an H voice when she transforms. Moreover, from that day on, Arisa is forced against her will to fight a secret society of evil. "Oh, I want to tell my feelings to Matsumoto-senpai, the man of my dreams, but only when I do so, I transform into an H battle suit."