The Love Letter, a Staple of Shoujo. Usually left in a locker, or delivered by a trusted friend when wanting to stay an unknown admirer.

In This case...maybe a Necromancer girl sent her disguised Skeleton to deliver a Secret Admirer love letter to that Knight she wishes would come and stop her, and then she could get married like all those other evil necromancers that try and get noticed....I mean try and take over the world with a legion of undead that fall apart so easily....

So have planned a Shoujo short of Irony