How do you keep someone as powerful as Ryoko captive for 700 years? What really kept Ryoko prisoner for so long were her own gems. With Ryoko's gems embeded in the master key power radiated to Funaho alowing it to keep it's power, although the tree had rooted. The combined forces of the gems in the master key, and Funaho's roots were more than enough to keep a powerless Ryoko imprisoned for almost a melenium. There is also the issue of how Ryoko was released. Although it looked like it had a lot to do with that rock Tenchi cut in half it's really much simpilar. Ryoko was freed because Tenchi wanted her free. Tenchi subconciously used the master key (just like he did in Ayeka's ship) and removed Funaho's roots from the immediate entrance to Ryoko's prison. He than oppened the entrance and found the "demon" that had both haunted his mind, and watched over his physical body since he was a child.
