This anime used to show on late at night on cartoon network/ toonami or adult swim. I want to say it showed somewhat early 2000's, but some time after 2003 or 2004. I can't recall if it was in english or Japanese. The show was about a boy who accidentally found a magic stone in a river that sent him somewhere else. There's a female. A princess, I think? She's in a coma or under a sleeping spell and lives in this robotic monster that if I remember correctly looks kinda like a robotic nessie (the sea monster). She lives in the back of the robotic monster in what looks like a glass case. The boy and the monster and their friends are on a journey to pretty much wake her up. It was a very kid-friendly anime if I remember correctly.