Ruby is a Japanese hare Jewelpet who represents Luck and Courage. She is the main protagonists' partner in each series and the very first Jewelpet in the roster overall. She is also the most notable mascot of the franchise.
Ruby and her partner(s) are appointed to find the other missing Jewelpets on Earth and handle every problem they encounter.

Spoiler

Ruby can also use the Jewel Pocketbook to awaken Jewelpets from their jewel forms. She can also wield a miniaturized version of the Jewel Stick to summon other Jewelpets from Jewel Land.