Go! Princess PreCure - Season 1 - Eps 13: A Cold Timbre...! The Black Princess Appears!
Haruka becomes interested in the violin after coming across a mysterious masked girl and coming to admire her violin playing. Minami takes Haruka to meet her violin instructor, who gives her a violin of her own, which was the first one he ever made. After struggling to play under Miss Shamour's instruction, Haruka once again comes across the masked violinist, who teaches her how to play. The next day however, Haruka and the others discover the masked violinist is actually Dyspear's daughter, Princess Twilight, who uses her own Dark Dress-Up Key to power up Shut, who in turn target's Minami's instructor to create a powered-up Violin Zetsuborg. Despite their opponent being stronger than usual, the Cures manage to defeat the Zetsuborg, after which Haruka manages to play the violin from her own heart.
About Go! Princess PreCure

Title: Go! Princess PreCure
First Air Date: 2015-02-01
Last Air Date: 2016-01-31
Status: Ended
Rating: 9/10 (from 10 votes)
Language: JA
Seasons: 1
Total Episodes: 50
Network: HTB tv asahi Nagoya TV Kyushu Asahi Broadcasting ABC TV NCC Oita Asahi Broadcasting Asahi Broadcasting Aomori Niigata Television Network 21 khb KFB HOME KSB Kagoshima Broadcasting Iwate Asahi TV Akita Asahi Broadcasting Yamagata Television System Shizuoka Asahi TV Asahi Broadcasting Nagano Hokuriku Asahi Broadcasting Ehime Asahi TV Yamaguchi Asahi Broadcasting Kumamoto Asahi Broadcasting Ryu-Q Asahi Broadcasting
Genres: Kids, Animation, Comedy, Action & Adventure, Family, Drama, Sci-Fi & Fantasy
Production Companies: Toei Animation
Synopsis
Go! Princess PreCure is set in a boarding junior high school, named Noble Academy. The protagonist Haruka Haruno is a 13-year-old first-year student. Her big dream is to be a princess someday because she admired a princess in the picture book she has kept since her childhood. One day, she transforms into Cure Flora with the "Dress Up Key" which Prince Kanata of Hope Kingdom gave her as a good luck charm when she was little. Then she also finds other Pretty Cure girls in her school, 14-year-old Minami Kaidou as Cure Mermaid and 13-year-old Kirara Amanogawa as Cure Twinkle. As the Princess Pretty Cure team, with two fairies Pafu and Aroma, they fight against the dark witch Dyspear, who hates all the dreams in the world and wants to turn them to despair.
Cast

Yu Shimamura
Haruka Haruno / Cure Flora (voice)

Masumi Asano
Minami Kaido / Cure Mermaid (voice)

Hibiku Yamamura
Kirara Amanogawa / Cure Twinkle (voice)

Miyuki Sawashiro
Miyuki Sawashiro as Towa Akagi / Twilight / Cure Scarlet (voice)

Nao Toyama
Pafu (voice)

Shiho Kokido
Aroma (voice)

Haruka Yoshimura
Yui Nanase (voice)

Mayumi Shintani
Miss Shamour (voice)

Shinnosuke Tachibana
Prince Hope Grand Kanata (voice)

Yoshiko Sakakibara
Dyspear (voice)