Kokoro is a neighborhood kid who crosses paths with Jahy. She's genuinely kind—when she notices Jahy searching for something, she jumps in to help without hesitation. Kokoro buys into Jahy's whole magical gem story pretty easily and thinks her transformation ability is genuinely cool. She doesn't actually manage to track down any gems, but she does find a four-leaf clover and gives it to Jahy as a gift. It's the kind of thing you'd expect from her: she just wants Jahy to be happy and figures a little luck wouldn't hurt.
Content compiled by AnimeList.moe from publicly available sources.
