Oneechan ga Mamotte Ageru!お姉ちゃんが守ってあげる! ; I will protect my Onee-chan! ; Onee-chan ga Mamotte Ageru!

Kairi Shinonome's younger twin brother, Anri, has been dressed as a girl since birth by their mother. One day, Anri goes to an idol audition. Kairi cross-dresses as well to go and stop him, but unexpectedly they both end up scouted as idols!