Oyuki is the very placid and graceful Queen of Neptune and is another one of Lum's alien friends.

Being from the frozen planet of Neptune she has the power control the elements of ice and snow. She also has an ability to utilize existing space/time warps to travel from planet to planet.

Oyuki is always proper and ladylike. She never shows strong emotions and remains the picture of demurity under any circumstance. She is nearly always very kind and sweet to others and speaks in highly dignified and polite manner. While everyone else around her tend to lose their tempers and lose their rationality, Oyuki is the only one who keeps her cool.

But never, ever get on her bad side. When Oyuki becomes angered you better run for the hills and keep running. On the rare occasions where Oyuki does get mad she doesn't appear to be angry on the surface but she gets a serious look on her face as the temperature surrounding her starts to drop drastically. Suddenly her ice powers go absolutely haywire. Ice, wind and snow rage causing unparalleled carnage and sealing any unfortunate passers-by in a block of ice.

Clearly Oyuki does have emotions like everyone else but her expression never changes much. It's almost scary because you never know what's really going on in that head of hers. Often it's obvious that what she's saying doesn't necessarily reflect what she's really thinking.

The ice queen is also a very skilled business woman. She is a bit stingy with her money though. She is hesitant to lend out anything of hers, and anyone who tries to swindle her even out of some pocket change will be subject to her icy retribution. Oyuki is knowledgeable of many alien races. This is because of her many business transactions with beings from all regions of the universe.

Oyuki is almost always hanging around with Benten. They are very good friends which some may find strange since their personalities are exact opposites.