Himitsu no Otome ~Boku ga Onna no Ko ni Natta Wake~

Kazuki Kurachi, heir to a dojo, is forced into women's clothing by his sister. While in disguise, he thwarts a bank robbery and saves a hostage girl, who—impressed and unaware of his true identity—hires him as her personal bodyguard. To fulfill this role, Kazuki enrolls in an all-girls school as a female student named Natsuki, embarking on a secret-filled new life.