A member of the 104th graduating class and a close friend to Krista, to whom she holds romantic feelings. Like Eren, she has the ability to transform at will into a Titan. Her Titan form is only 7-meters tall, but she is easily the most nimble of the Titans, taking down several that are larger than her using only her speed, claws, and teeth. She is ultimately defeated at Castle Utgard and seriously injured, and is captured alongside Eren by the Colossus Titan and the Armored Titan after their identities are all revealed. Ymir admits that she has become human and enjoys doing so because of Krista, as well as revealing that she existed as a Titan outside Wall Maria for over 60 years. During this time, she ate one of Reiner's and Bertolt's close friends that they made while infiltrating humanity. Initially resisting against Reiner and Bertolt's efforts to capture her and Eren, Ymir later decides to assist them after they assure her that they can protect Krista as well. However, she soon abandons both Reiner and Berthold to the other titans and instead choosing to follow Connie when he saves Krista, making him realize that Ymir is only serious when she needs to protect the one she loves. She then realizes the reason Reiner and the others were interested in kidnapping Eren. Before returning to assist them, Ymir tells Krista to leave with the other Survey Corps.