Ultra Maniac - 1x03 - Season 1, Episode 3- Followmy.tv

Ayu must battle Tsujiai in a tennis match to decide which tennis team gets three tennis courts. To make things fair, Nina turns Ayu into a boy to help her win a match with Hiroki, but the change in height makes her lose. After that, Akiho, Tsujiai, Kaji, Nina, Ayu, and others go sing karaoke. Nina turns into a boy too and Ayu stays a boy. While there, Ayu tries to prevent another girl from flirting with Kaji.