"I think I can write," Sizhui says after a moment of thought. He'll at least try, he's not thinking about them recognising her calligraphy, but he is thinking that seeing a letter written by somebody else would make them suspicious and bring them here all the faster.

He just hopes his hand is steady enough for it.

And that he can phrase what's going on in a way that doesn't make them immediately worry anyway...

In the end, when she does bring him the ink and paper he manages to compose something reasonable - he explains that the trip is taking longer than expected and that he will be a few more days in town, but that he will write again in a couple of days with an update. He's deliberately vague about why it's taking longer, and hopes they'll interpret that as the night hunt itself taking the time, since they'll be less likely to come rushing into town if they think he still needs to complete his task so he can graduate. It feels a little too much like subterfuge for his liking, but at least it buys him some time.