Cosplay transmigration is just a matter of closing your eyes and opening them again.
For one reason or another, your cosplay is the villain from the final Gintama movie, Enmi.
Written as Enmi, pronounced Sakata Gintoki, but gender-swapped.
The director's major rewrite of the script means you've transmigrated with a controllable doomsday virus inside you. It's extremely contagious, and if it gets out, either you'll die or the whole world will perish along with you. This... is a lot of pressure.
You: ...I really can't thank you enough, Director.
Second-person narration, with plenty of headcanons. Also, look up how to pronounce Jue for a fun surprise. The female lead doesn't know the plot or anything about Jujutsu Kaisen.
Theme: Everything you seek comes at a price
Nice!!! Why are there things waiting for review at the end? Woohoo.