Crystal Yuki is the main female protagonist of the fanfiction story Learning to Love with Zane Truesdale being the main male protagonist. She is Jaden's younger twin sister, and has a great dark power in her that keeps her from dueling, with her full strength. She was worried she will hurt anyone, everytime she duels, even against Jaden in their childhood, when Jaden still has Yubel. She is also the girlfriend of Zane Truesdale.