At this point probably Whiskey and Kitsunebi, though he's not terribly close to either! Whiskey is obviously from his world and is a potential source of information that's fun to poke into flailing, and Kitsunebi is.....well. Cat isn't sure what's going on there. But Kitsunebi seems fun to be around and after their little pounce fight while they were deaged he feels...a bit of connection with him. So there's that.

How does Naha feel about being part of a heart game?