Mayuka Masaki (柾木 麻由華, Masaki Mayuka) is one of the the main characters of the second Tenchi Muyo! movie Tenchi Muyo! Daughter of Darkness, which is set in its own standalone continuity. Mayuka is the daughter of series protagonist Tenchi Masaki and the demon Yuzuha.
Mayuka was created by Yuzuha, using her and Tenchi's DNA, Yuzuha planned revenge on the Prince Yosho of Jurai as a result of an incident that occured on planet Jurai when they were children so she set her sights on his heir, Tenchi. Mayuka is only 1 but she has been aged to look like she is 16. She acts very youthful and playful around everyone. She has brown eyes like Tenchi with blue and silver hair. Mayuka was sent to Tenchi as a present, making the extended Masaki family believe that she is his daughter from the future. 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. Kiyone also enjoyed having Mayuka around. Mayuka began to develop emotions at this point, much to Yuzuha's disgust. Yuzuha began to manipulate her to resume her old mission of kidnapping Tenchi. Curiously, she showed that she has the ability to generate one Light Hawk Wing, proof that she is Tenchi's offspring because he is the only human being that can do so.
Once Mayuka's true nature was revealed, Yuzuha erased Mayuka's memories and ordered 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 while 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.
At the end of the movie, she is resurrected by Washu as a baby to be able to live life with Tenchi's family without Yuzuha's interference.