La Belle Fille Masquée Poitrine (美少女仮面ポワトリン Bishōjo Kamen Powatorin, The Masked Belle Poitrine) is a magical girl tokusatsu comedy series created by Shotaro Ishinomori, and the 11th installment of the Toei Fushigi Comedy Series. The series ran from January 7, 1990 to December 30, 1990 for a total of 51 episodes.
It's the first day of the new school year and the Murakami kids, Yuko and Takuto, are excited to be heading back and catch up with their friends. While Takuto makes it to school, Yuko stops by a shrine that doesn’t get too many visitors these days to pray for the new school year. At the shrine Yuko accidentally breaks the bell and drops it on top of the Kami's head. Because she is the only person that stopped by the shrine in a long time, He grants her the power to become a superheroine, based on another ancient goddess. It is her job to protect her neighborhood from the threats it faces. With the transformation phrase "Cosmo Magic! Métamorphose!!" (コスモ・マジック! メタモルフォーゼ!! Kosumo Majikku! Metamorufōze!!) she transforms into the Masked Belle Poitrine. Later she gets an ally in Poitrine Petite, in actuality her little sister Momoko.