The series/model number for
Genoms line of sexually active or
sexaroid boomers. The 33-S's had an artifical blood supply, so when they became damaged they had to find suppliments or shutdown. They were pulled from the market in the early 2030s, but Genom still sells a couple here and there. For some reason, there was a group of 33-S's on
Generos, and they stole a shuttle and eventually made it Earth,
MegaToyko to be exact. Although, not all of them made it....
For more information please watch the original
Bubblegum Crisis episodes five (Moonlight Rambler) and six (Red Eyes).