Naegi is under suspicion of treason so in the manner that all brilliant horror movies start all the ‘good guys’ conveniently gather in one place so that of course the enemy can lock them in and play a game.
I’ve never played any of the games or read any of thing connected to this series. I did watch the original anime and while I found it interesting enough it wasn’t something I loved. This anime seems to be fairly similar. They give us a lot of exposition to catch us up with the current circumstances, rush through some bickering between characters who, for some reason always stand quietly while the villain talks and wait for a pause before objecting, and it ends with a bloody murder of some description. For someone who hasn’t followed the franchise, this is watchable enough and neither particularly good or bad. I do however find the whole thing interesting but I’m just not sold on committing to it given how much information I’m missing and how generally disengaged I was with the last anime of this I watched.
Danganronpa 3 is available on AnimeLab.