Nakuru is Touya's new classmate in Seijou High. Her first appearance in the series is the same day Eriol arrives, and the first thing she does (in front of the screen, that is) is GLOMP Touya...the very same way (even worse, actually) Meiling does to Syaoran. She has a BIG crush on Touya-kun and always calls him "her delicious feast". He's not too happy about that.
Nakuru has a secret. She's not a she. Well... she's not exactly a he, either, but Nakuru prefers to look like a girl. OK, she's not human...just like Yue. Nakuru's true form is Ruby Moon, created by Eriol.
Nakuru is also overly hyper. She's as hyper as Yue is serious. She was created as a opponent against him, too. And, she's also VERY strong. I has lots to do with Eriol being half of Clow.
Nakuru is usually there...doing nothing while in her true form. Most usually, she does the job Eriol told her to do in her false form (Nakuru). And, though, most usually, Eriol doesn't tell her why she's doing all that stuff for, she just follows...and she does her job precisely well...Just the way Eriol wanted it.
Spinel Sun was a creation of Eriol to be an adversary against Cerberus. His true form looks like a panther with black butterfly wings. He has this green gem on his forehead, and when Eriol wants it to, the gem turns red, and Spinel Sun's power increases big time. He's very strong, actually. He breathes (?) red beams, very much similar to the way Cerberus breathes fire.