Sorincha  

Oni, ソリンチャ

In the Japanese version of the movie, Hikora refers to his sister as "Imoto," which means "younger sister." Based on this information, it can be assumed that Sorincha is Hikoras younger sister. She played the game O-to-ko-yo but did not return after. Her possession by a demon was indicated when her mask changed to that of a demons at the end of the movie. It's believed that she was possessed because she was the last kid left and didn't get caught before the game began, and her mask was put on her as "it" for the next round. The fate of Sorincha after the game is unknown, as she is not shown at the end.