Ymir's Titan (Anime)

The Dancing Titan is an intelligent Titan and the Titan form of Ymir.

Story
At some unknown point and time, Ymir gained the power of the Titans. During the Wall Rose invasion, Ymir is among the recruits of the Scout Regiment at Utgard Castle when it is overrun by Titans commanded by the Beast Titan. When their commanding officers die confronting the Titans, Ymir speaks with Christa, reminding her of a promise they made to each other during their training days. Taking a knife from Conny, Ymir slits her palm and transforms to fight the Titans at the base of the castle.