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Yume attended the Jurai Science Academy at the same time as Washu Hakubi. Yume graduated second in their class, with Washu ranked first. Unlike Doctor Clay, Yume was actually considered by Washu to be a legitimate rival whose intelligence was worthy of respect.
In addition to their intellectual competitions, Yume also engaged in drinking contests with Washu at a bar near the Academy. After one of these contests shortly before Washu's capture by Kagato, the highly inebriated geniuses agreed on a contest to see who could conquer the Jurai Empire first, with the loser becoming the winner's slave. While Washu passed out afterward and promptly forgot about this wager, Yume dedicated herself entirely to winning the competition. She created three powerful warriors, the Shima Brothers, to carry out her plan, and stole the 2nd-generation Jurai royal tree Bizen. Yume then placed herself in suspended animation to wait for them to acquire the Jurai Book of Secrets, which contained information she needed to control Bizen's powers.
When the Shima Brothers finally awakened Yume, she was angry that they had taken 7200 hours longer than she had predicted. Yume also declared herself to be "the greatest scientific genius in the universe", a title which Washu also frequently claims. She proceeded with her plans, using information from the Book of Secrets to activate Bizen and launch the enormous tree into space. Mihoshi's spaceship Yukinojo, which had secretly followed her to the planet Ryuten, was the first to encounter Bizen, and was quickly overcome by the tree's Light Hawk Wings. Yume left Yukinojo intact so that Bizen's appearance would become known to Jurai.
In response, Jurai's queens Funaho and Misaki deployed the entire Jurai fleet to recover the stolen tree. However, Washu was able to locate Yume first, and challenges Yume with a new wager: a fighting competition where if Washu wins the previous contest is cancelled, while if Yume wins Washu will become her slave. Instead of fighting herself, as Washu had hoped, Yume instead sent Takashima and Hishima to fight on her behalf. Tenchi and the monk Gohgei volunteered to represent Washu. While Gohgei easily defeated Takashima, he proved no match for Hishima. Tenchi then stepped up to fight Hishima, but their battle was interrupted by the arrival of the Jurai fleet. Yume used Bizen to seize control of the Jurai warships, but Tenchi resumed the fight with Hishima to force her to give up. With his Light Hawk Wings, Tenchi was able to defeat Hishima, causing a large branch from Bizen to fall toward Yume. At the last moment, Takashima sacrificed himself to save his master, leaving Yume distraught, as she had never wanted anyone to die for her.
The damage to Bizen caused the tree to completely lose control, initiating a chain reaction that could potentially destroy the entire universe by detonating itself and all the other royal trees of Jurai. Yume worked together with Washu in an attempt to avert this crisis, and they realized that the only way to stop the chain reaction is to kill Bizen. However, before they could complete their task, an enormous extradimensional energy distortion, resembling a black hole, formed around Bizen. However, at that point Tsunami appeared and averted the crisis. Washu convinced the Jurai queens to allow Yume to go free, and later she and Hishima visited an onsen on Earth at Washu's invitation.