[quote=@Inkarnate]
 how much do we, as a group, want to focus on the duels? I’ve seen several approaches to the genre where the out-of-duel interactions are more important as opposed to the “dueling” being the most principal important factor. Will this have a school setting or a tournament setting or somewhere in-between? What is the hook, what brings the protagonists together?
[/quote]

1) The setting will be somewhere in between. Take pacing from other card game animes. There will be slice of life moments where the students can have down time, have dates maybe. There will be tournament arcs. And maybe even some fantasy adventure moments as well as they try to uncover the mysteries of the World Ends. 

2) What brings the protagonist together is that they all acquire in some mystery way a World of End card. They are a card that exist nowhere in the original print of the cards that currently exist. That have mystical powers. That tie to them an ancient tale. They will acquire a Warrior of World End as an alternative persona, like a ghost that takes over a host body when they duel or when there is an adventure that is going on or some kind of connection.