Matte! Sailor Fuku Kishi

Maiko Hoshino, raised in a martial arts family, is a seemingly normal high school girl who attended Sankagetsu Gakuen. However, she has a secret identity as the Sailor Knight, the heroine who stood up to the delinquents that infested the school. Her heart was conflicted between her desire to be a "normal, pretty girl," her sense of justice for fighting evil, and her feelings for her oblivious childhood friend, Tatsuya Aikawa. (Source: Mangapedia, translated)