What’s makes this even more funny is that Remilia canonically does sleep in a coffin. "In Curiosities of Lotus Asia Chapter 4, Reimu Hakurei comments that Remilia should go back to her coffin. Remilia retorts that coffins are for the dead, indicating that she doesn't sleep in a coffin. In Imperishable Night's Scarlet Team Scenario, before battling Reimu, Remilia once again reminds her that she doesn't sleep in a coffin. Finally, in Oriental Sacred Place Chapter 15, released 7 years later, what's apparently the first canonical depiction of Remilia's bedroom is shown, and that she sleeps in a coffin (on a bed)". - Touhou wiki
I love that across the series, Remilia continually basically says "no, I don't sleep in a coffin, coffins are cringe and for dead people!" And then she does, in fact, sleep in a coffin.
How rude for the shrine maiden to show up like they're about to Belmont the place up. And she even brought the one who has been "borrowing" stuff from the library with her.