Nashi, also sometimes called Nettle, is a hedgehog Forest Folk. (Naoki is going to hate every minute of this.) He didn't originally set out to research the going-feral problem, but then it struck his older sister Sakura. She wandered off and hasn't been seen in a few years; he's hoping he can find a cure before the average lifespan of non-sapient animals catches up with her.

(Did I mention Naoki is going to hate every minute of this?)