Help on finding an anime

Spacehey is slowly dying unfortunately but I just wanna ask this because one of my friends have been searching for a while.

They've been looking for an anime that had this scene: There was this little girl at a carnival with this older girl, and she was wearing a hat that fell off and there was this monster thing on her head that killed the other girl. Any monster would be possible but it could have been a tentacle one.

If anyone can tell me what anime that scene came from, let me know.