An expert mechanic. She helps Sho's group on different occasions.

After Gabu's defeat, it was revealed that Yuki is a princess of a royal family with Hosuke being her grandfather. Also, Yuki is part of a group who protects the X-Zone and the secrets of the X-Zone.
By the end of the series, it is revealed that Yuki is the granddaughter of Hosuke's human form.
(Source: Wikipedia)