She is a relatively short girl. At best, she only reaches Alma's midsection and is a few inches shorter than Wakana. She has long red hair and green eyes.
Ruri has shown a few sides of her personailty that could be considered contradicting. she is very knowledgable in matters conserning business as she is able to manage her families corporation, serious when fighting the dark stones, niave when it comes to mundane matters like what the pinky signify in japan (this was humorously shown unowingly admiting that she was Alma's girlfriend as she said "she was his" and raising her pinky finger) it is shown a few times that she can have a stuborn streak.
5 years before the story line, Ruri is the only one of her family to have avoided any injuries when zero assaulted their vacation home on christmas. This was due to the present Aoi and Ruri were making for their parents broke. Ruri wanted to fix it. Because of her stuborn streak, she refused to leave her room untill she was done fixing the present. It was actual, because she managed to avoid the worse case scenario. Her parents were obviously not lucky, and Aoi's powers activated out of self preservation and encased her in crystal.