H00439 Princess 69: Midnight Gymnastics Ep 1

A secret competition called dark rhythmic gymnastics exists, where entrants perfect their lewdness through difficult techniques. Haneoka Fubuki searches for his missing sister Miku and finds her at the house of her classmate Tomomi. Tomomi says Miku is trapped in the dark gymnastics world. To save her, Fubuki becomes a coach and approaches Fujimiya Koyuki.