Got it!

Nagito was the kind of person who was too suspicious to be suspicious- meaning, nobody actually thought he was the mastermind, even though he was certainly most likely to be.

His reasons for doing so were simple: he wanted to see hope overcome the largest despair he could possibly create for his classmates. What better way than a killing game?

Junko had been his driving force. The despair she created was a direct challenge for him to make his class overcome it. Who was he to not accept that challenge?

Which was why he subjected them to the killing game. After all, Junko’s own plan backfired and caused her class to feel hope over despair like she originally planned.

Ooo I like this one

Chiaki and Nagito knew of each other’s existence since the beginning of the game. For the most part, they stayed out of each other’s way, but were far from cooperating with each other.

No, they were mostly competing over two things in particular: causing the most despair, and winning Hajime. They both loved Hajime, and wanted him to be the sole survivor by their sides- but only one could have him.

So while they were orchestrating the game, they also kept spending more or more time with Hajime- as much as they could without letting him know that they were the masterminds.

It got kind of ridiculous sometimes. Sometimes they would try shoving each other over, sometimes into the ocean or onto the sand of the beach. The funny thing was, though, nobody else knew what was happening.