Mitsuki Amaki, Princess of Jurai and Azusa's first love
Mitsuki Amaki was the head of the House Amaki, though it was left for a proxy to fill the role for most of her life. She appears in True Tenchi Muyo! Volume 1: Jurai.
Early Life
Mitsuki Amaki was born on Jurai. She was the granddaughter of the emperor who proceeded Azusa Masaki Jurai. Her father was not Juraian, he was foreign born and was secretly a pirate spy. She manifested a special power allowing her to see everything inside of Tenju by synchronizing with it. When her father found out, he coerced her to reveal the secrets she learned. She was young and had no idea that she was doing anything wrong. When a prime minister of an ally planet was attacked using her information, Seto managed to figure out the truth through her spy network. Mitsuki's father escaped or died, it's unclear. As for Mitsuki, although she was young, it was a serious crime and she would have normally been exiled from Jurai as punishment. However, it was discovered that she needed the support of the 1st-generation trees of Jurai and to be cut off from them would mean her death. It was also decided that the truth (that a foreign spy raised so high in the family) could not be made public, as it would cause distrust among their allies. During the attack, it was actually Azusa's uncle, his mother's older brother, that saved the prime minister's life and he was also able to deduce the truth. A traitor in the family seemed a better option than a foreign one and he agreed to be the fall guy for the incident, as it had become public knowledge that there had been spying. Azusa's uncle was banished from Jurai forever. However, to prevent any more accidents, Mitsuki was confined to a special chamber and only the emperor was allowed to visit her.
She is also the aunt of Shuzan Amaki, who would eventually scheme to become emperor. and would become the proxy head of House Amaki while she was confined. He had no idea of the truth and believed that his aunt had conspired with a member of the Masaki House, which was almost as bad to him as the crime. It also hurt him greatly because, in his youth, he too was extremely fond of his aunt.
Meeting Azusa
Some hundreds of years later, she saw Seto teasing and chasing an annoyed Azusa (just a young teenager at this point) by her window and thought it looked fun. She used her powers to cause a transporter malfunction and while he was trying to escape Seto, he found himself in her room. He found her beautiful and captivating and they continued to meet in secret. She never told him about it being forbidden to see her, he just kept it secret because he didn't want others to know. Shuzan had set a maid to watch her room and discovered the forbidden contact.
Shuzan entered her room and eager to goad Azsusa and cause a scandal that could banish him, teased him about being ignorant and insulted Mitsuki cruelly. He thought goading him into a duel would be a good move and not dangerous, as he was just a kid. He let his guard down and was almost killed by him. In turn, he became angry and almost killed Azusa. Both being stopped by Mitsuki. Still, Azusa had broken the rules and Shuzan was able to bring charges against him and he was jailed (although able to escape).
Seto, however, found out about the maid (which was also an action that was against the law) and pointed out that Shuzan coming into Mitsuki's room in order to catch Azusa in the act was also something he wasn't allowed to do. So, when the trial was held, with Mitsuki surprising all by attending in her actual role as Head of House Amaki (displacing Shuzan), and the emperor immediately dismissed the charges, Shuzan was unable to argue against it. The emperor then further spoiled his plans by declaring they would instead hold Azusa's tree ceremony the next day.
Mitsuki again attends as a witness, along with the emperor, Seto, and Kotono Tatsuki, the head of that house. He was granted access to the Second-Generation trees (most royals are actually never granted access and only receive a third generation- like Shuzan) but none of them asked to be his partner, meaning only a First-Generation could. Mitsuki alone escorts him to their garden and brings him to her own tree, which she said was now his. When he said he can't hear the tree's voice, she tells him that he's hearing its voice at that moment. It seems then that she goes somewhat ethereal and part of her enters the tree. Her body collapses. She explains she doesn't want to see more people hurt by her, so she cut herself off from the Tree's power so it could choose Azusa instead. In her last moments, she shows him that one of her eyes is a prosthetic made from this tree and asks if he will take her with him now, as he once said he would. He agrees and she dies. After a long cry, he brings her body into the hollow of the tree and lays it in a pool of sap, where it sinks and is preserved in amber. Azusa names the tree Kirito, "Fog Seal," after a fairy tale she shared with him about the fog covering the sky and keeping the beautiful moon to itself.