Go! Princess Precure

Synopsis

After Towa wakes up at Noble Academy, Haruka tries to give her Kanata's violin, but she feels she isn't worthy of. Just then, they are both confronted by Dyspear, who is determined to bring Towa back to her side, trapping her in a tower of vines in order to draw power from her despair. As Minami and Kirara hold off Dyspear, Haruka breaks into the vine tower to rescue Towa, using the words Kanata gave her to encourage her dream. As the two girls combine their violin playing, combining into a single melody, Towa's black keys transform into new Dress-Up Keys, transforming her into the fourth Princess Pretty Cure, Cure Scarlet. Using Kanata's violin, which transforms into the Scarlet Violin, Towa manages to force Dyspear to retreat before assuring Haruka that Kanata is still alive somewhere.

(Source: Wikipedia)