Essentially the plot takes place during a festival in Academy City. You have A Certain High School participating, as with the other schools in the Garden of Education. There's mysterious stuff going on.
Some people are having nightmares of some chaotic event that's to come. It's up to the players if they want their characters to be 'targeted' by this nightmare and have them be semi-aware of the coming dread!
The plot would be a 1-week time-loop which gives time to experiment with character relationships and sub-arcs.
Oh right, Canon characters are definitely going to be allowed (given the context of the RP).
I'm going to take Kamijou Touma because PLOT reasons. Also Saten because no one likes Saten.