Also for your consideration: raccoon dog/tanuki Scuzz. Small canids that have very similar body language to cats, can climb, are nocturnal, and live in Japan.
But it doesn't really fit what I have in mind because Jonny is already a racoon for me. And even if it would be fun to have Scuzz being distrustful toward someone being this close of their specie, it would create a duplicate.
I prefer to imagine Scuzz as some kind of monkey like a squirrel monkey. Very agile, great climber, lives in group of different species, female squirrel monkeys show disadvantageous inequity aversion as it pertains to food rewards... It fits better the kind of person my Scuzz is.