Mayuka was created by the Juraian demoness, Yuzuha, using her and Tenchi's DNA, and was sent to the present time, posing as Tenchi's future daughter. Upon Mayuka's arrival, Ayeka and Ryoko took an immediate dislike towards her, but Sasami begins to like her, and even promised her that they would celebrate Christmas together. Mayuka began to develop her emotions at this point, much to Yuzuha's disgust, and she began to manipulate her to resume her old mission of kidnapping Tenchi.
Once Mayuka's true nature was revealed, Yuzuha orders Mayuka to kidnap Sasami, forcing Tenchi and Ryoko to go after her (Yuzuha) instead. She battled Tenchi and Ryoko, cutting Tenchi up with her claws whilst Yuzuha watched, but in the end Sasami got through to her. Mayuka managed to break free of Yuzuha's control and attacked her, clawing out her right eye and saying that she didn't want to fight. She was eventually "killed", but after he defeated Yuzuha, Tenchi brought Mayuka's crystal to Washu, and they all agreed to revive her as an infant, thus allowing her to celebrate Christmas with the gang.