Ryoko was partly genetically engineered by Washu 2000 years ago from one of her ova and a creature known as Masu. Therefore, Ryoko is technically Washu's daughter. Washu created her to be used by Kagato (not of her free will). She was forced to plunder the universe as a space pirate, but she attacked the planet Jurai. Yosho chased her down and caught her and took her gems away, leaving her helpless so that he could seal her in a cave for 700 years. All of Ryoko's powers are generated by three red gems; one in her neck, and one in each wrist. They allow her to create an energy sword to weild/throw, throw energy blasts,teleport, walk through walls, fly, telepathically communicate with Ryo-ohki and Washu, create a huge hammer from the space behind her back, etc. etc.

Ryoko observed Tenchi from from her prison cave since the day he was born and gradually grew to love him. When she was freed, she wanted revenge, but soon settled down and was no longer controlled by Kagato. Ryoko obviously has the hots for Tenchi. She constantly fights Ayeka for Tenchi's affections.Sadly, he does not seem to observe it taking the opposite effect. Ryoko enjoys soaking in the hot springs, drinking sake, fighting with Ayeka, and seducing Tenchi. At the hotsprings, unlike Ayeka, Ryoko often goes sans-towel, making her the notorious exhibitionist.