The ones who really saved Arakawa from Ric's dad.Since we know that while the residents are Cloudcuckoolanders, some of them are more capable then they appear... The facial expression and hair on the bottom-left is just so Kappa. And the man in the yukata, can that be Billy? Although, his facial features seems more Whitey-like.
Everything and everyone under the bridge only exists in Nino's mindGiven various hints dropped in the anime, it seems to be implied that Nino is schizophrenic and Ric, Sister, and everyone else exists in her mind, and she just lives under a normal bridge.