Ryo-Ohki is a part-mineral, part-organic life-form First seen in the OVAs in the form of Ryoko's spaceship, she later crashes and produces an egg. The egg hatches into a cabbit (half-cat, half-rabbit), which is the form Ryo-Ohki is seen in most often. She is capable of transforming into a spaceship again at will. In the OVA series, she gains the ability to change into a humanoid version.

In the second TV series (Tenchi in Tokyo), she is owned by Sasami, not Ryoko. In the series, she can also transform into a large mechanoid cabbit, which can act either autonomously or with Sasami as the pilot.

She adores carrots, and is most friendly with Tenchi and Sasami (she often rides around on top of Sasami's head).

* Birthdays indicated are taken from Japanese seiyuu's birthday, as opposed to any official date.