The Reze arc ends on chapter 52, and part 1 ends on chapter 97. So 45 chapters in 12 episodes would be slightly more than season 1, which adapted 39 chapters in 12 episodes. They could speed up the pacing or do 13-14 episodes. Either way, I think a second season after the movie will definitely wrap up part 1.

I’m really glad they’re making the Reze arc a movie, it’s the most standalone arc out and is structured pretty well for movie format. There’s a lot of buildup with Makima and Denji at the cinema, Aki and Angel and Denji and Beam’s interactions, the dates with Reze, and Reze’s reveal should come around the end of the second act. There’s not really any action at all until the fight with Reze, and then it’s a massive fight, so it’s a good set up and immediate pay off.

Also if they didn’t do it this way, a second season would either have to be longer or cut off right after the international assassins arc which would make the final arc seen very seperate