Rudy is Jibanyan's former living self before he got hit by a truck. He bears a similar appearance to Jibanyan, even if resembling a more normal cat. Rudy is a red and white kitten wearing a gray collar with a blue tag on it. The tag is as shiny as a crystal.
According to Jibanyan’s flashback, he mostly slept all day and had no real personality outside of that.
Despite being Jibanyan's living self, Rudy is one rank higher than Jibanyan is currently. Jibanyan may be considered weaker post-death.
Technically Rudy shouldn't be a Yo-kai, as he's still alive, and Jibanyan only became a Yo-kai after death. This is likely because when Rudy died, his soul came out and became Jibanyan, the corpse still remained, implying corpses can still move in the yo-kai World, implying more yo-kai such as Rudy might do the same, although this is still not comfirmed.
The names Rudy and Akamaru describe the red color of Jibanyan.