Mysterious Girls? The Bequeathed Legendary Key! (ふしぎな女の子？受けつがれし伝説のキー！Fushigi na Onnanoko? Uke Tsugareshi Densetsu no Kī!?) is twenty-ninth episode of Go! Princess Pretty Cure.
- Air Date:August 23,2015
- Previous:Episode 28
- Next:Episode 30
- Opening:Miracle Go! Princess Pretty Cure
- Ending:Dreams are the Path to the Future
- Chieri, Yura and Sei, the previous Princess Pretty Cures, appear for the first time, and their Pretty Cure forms are fully shown for the first time as well.
- Lock's despair gauge is filled all the way up. This is the result of getting despair from the nine Dress Up Keys that he stole in episode 28.
- Haruka, Minami and Kirara receive their fourth Dress Up Keys, which are known as the Premium Cherry, Coral and Galaxy Dress Up Keys.
The trio were depressed that their Dress Up Keys are taken by Lock. Towa and Yui comfort them and they find a way to get the keys back. At the Dys Dark, Shut was shocked that has three Locks with the Dress Up Keys and trapped the keys to fill the gauges and reach to maximum along with Shut's. Puff dream about the Dress Up Keys and the Cures follow her but ended up being separated from Towa and Yui. The trio encounter the mysterious girls named Chieri, Yura and Sei. Who explain they lost their things but they were confronted by Dyspear, who created a Soldier Zetsuborg. The trio realises that they don't have their Dress Up Keys to transform and they escape but the thorn keep restrain them. Realising that they cannot give up their dream, Chieri, Yura and Sei call their Cure's name and give them their Dress Up Keys to allow them to transform, Twinkle distract the thorn while the two hold off the Zetsuborg and Twinkle lead the thorn to attack it before using Floral Tourbillon, Mermaid Ripple and Twinkle Humming to defeat it.
The three girls revealed that they are their former Cures and give them a Premium Cherry Blossom, Coral and Galaxy Dress Up Keys to them before they departed. They teleported back and reunited with the other. At the Dys Dark, Lock turn the palace into Zetsuborg and teleport it to the Earth as he prepare for battle, which the Cures were shocked.
- Haruka Haruno/Cure Flora
- Minami Kaido/Cure Mermaid
- Kirara Amanogawa/Cure Twinkle
- Towa Akagi/Cure Scarlet
- Dyspear (Hologram)
- Yui Nanase
- Seira Azuma
- Past Princess Pretty Cure
- Cure Scarlet perform a solo in the middle of the ending.
- The previous Princess Pretty Cure's Mode Elegant looks exactly the same as they appear as silhouette from Kanata's story in episode 6.
- This is the first episode where an object (both the Dress Up Keys and the castle) is used for creating a Zetsuborg.
- The way the Zetsuborg came out of the sky is a reference to Doki Doki! Pretty Cure, due to how the Selfish King came out of the sky in episode 47.
- This is the first episode in which Towa did not transform into Cure Scarlet since she became a Cure.