Inside the charm, they'll find a piece of paper that looks like an ofuda. The characters at the top of the paper appear to be a spell for misfortune, but at the bottom of the paper there are a number of symbols that are unfamiliar to all three of them, and not apparently in any human language.

There's also a small, flat piece of streaky acrylic plastic folded inside the piece of paper; it has a few mysterious symbols on it that match the ones on the paper.