Sou Hiyori

Sou seems like a simple friendly guy at first, originally getting along with the group. It was soon shown this was all to get the trust of the other students so he can break off from them and cause some trouble hoping for his own survival. He pushed others away and when he didn't he usually had a reason not to. Though becomes more self aware and accepting later on.

Chapter 1
Sou like the others was trapped in a school and forced into the killing game. He reacted similarly to the others are panicked but ended up going on with the groups attempt to escape. He seemed to somewhat hoard what he can and asking people for things they got or found to keep. In the hallway he even made an attempt to attack Ryoma but made it all look like an honest mistake while messing around. Soon the time came and Sou had a plan to scare everyone off, so nobody would get to close to him. There was an incinerator where the trash went daily where the first killer, Ryoma Hoshi, burned the trash to keep the school clean. Sou Hiyori made a plan and knocked out Izuru Kamukura then left him in the incinerator, so when Ryoma activated it he would be burned alive and make Ryoma the blackened.

Chapter 2
Sou's plan was complete and nobody wanted anything to do with him.. He figured he could do as he pleased and go on with his life alone, until Kirumi Tojo came up with a plan. She needed help with it though and hearing of Sou's past acts figured he'd be fine with assisting. He wasn't crazy about being involved again but did it anyway as he really had nothing to lose if she got caught. He assisted in the plan sneaking around and using outlet's to cause electricity. Kirumi ended up being caught and he was revealed to have been a part of it again. By this point even the most trusting people didn't want him with the group.

Chapter 3
The new motive of the "despair disease" caught Sou's attention as several students acted differently around him and others. Sou faked having this disease and revealed faking it later on. During the trial proven Kanade was involved he tried to have everyone convinced she was a bad person. He continued this till the near end.

Chapter 4
Sou didn't pay much mind to anyone and did his thing. During the trial he hid some small pieces of evidence but didn't care too much what was going on.

Chapter 5
Sou decided it was time to end the game. Not many people trusted Sou but he started to actually like some of the people there, as some still tried to talk to him or help him. He wanted it to end and was willing to risk it all. He set up a plan with Rantaro Amami for his death to be made to appear as if Rantaro did it while it was actually Sou himself.

Chapter 6
Sou was dead, but his plan had worked and the evidence of his suicide was found by the group and Monokuma was beaten.. Sou was brought back with his memory with the rest of the cast and decided to apologize to everyone. Most people even forgave him, he did help everyone in the end and now everyone was free.

Monokuma
Sou liked Monokuma to start, sure he captured them but he know Monokuma couldn't kill him so he didn't mind being friendly with him as much. The played Uno and go fish and other card games to make time pass. Near the end when Sou decided to escape his plan for obvious reasons upset Monokuma.

Kaede
Kaede tried and tried to make Sou join everyone and have hope, natrually he declined even occasionally snapping at her and telling her to just leave him alone. She stopped trying for a little while but just went back to it and probably would've repeated that cycle had the game not ended. When brought back they were on neutral to friendly terms mostly.

Rantaro
Didn't speak too often throughout the game in general and more or less stayed out of each others way besides a few interactions. Rantaro was clearly annoyed with Sou during trials as he liked to hide evidence or just be an actual part of the crime. When the plan succeeded they seemed pretty happy and can be considered friends in a way.

Kanade
Sou had a hate for Kanade in general just deciding her as a target for random accusation in trials or warning others not to trust her. Kanade didn't like him either showing clear annoyance and anger at him sometimes just telling him to shut up even in situations where he'd need to speak like trials. Sou did apologize to Kanade after the game ended and she seemed happy to finally recieve an apology.