Her name is Chitose. She's the oldest of the village children attending the temple school, and with her curiosity and vigor, she's quick to be social even with youkai.

She gets along especially well with Rumia, to the point that they have nicknames for each other.

Ru-chan, see you tomorrow!

You've sure become good friends with Chitose, Rumia!

Uh-huh, I liiiiike Chi-chan!

That's right, friends are important!

Maybe she just couldn't leave Rumia spacing out somewhere.

Rumia's become pretty attached to her, too.