Monokuma

Personality
Monokuma starts off as a comically evil mascot, portraying himself as very over-the-top and generally isn't too feared by the students (who mostly carry more spite towards him than anything. He does very minorly evil things, such as eating the food of the participants, and giving people petty nicknames. This facade ends after the game progresses, to which Monokuma becomes very antagonistic. He changes things in the game just to mess with the participants and to ensure the game goes smoothly, and frequently mocks the memory of dead participants. He seems to know when he's defeated, such as in chapter 6 of CoD, where he executes himself because he technically executed an innocent student.

In Chained Hope, Monokuma has two personalities, one being the 'Headmaster', the more antagonizing and cruel one, and the 'Tour Guide', who is generally good natured and tries to help the students out in any way that doesn't directly impact the game.

He is also shown to be able to grow attached to certain students, which shows in his rebuttal showdown during the chapter 3 trial of CoD.

Chapter 1:
Monokuma introduced himself to the seven students, informing them of the Killing Game. He gave them set rules on the Monopads, and allowed them to explore the first floor of the school. After a few days, he opens the second floor as to give the students something to search for, on that day he also gave Ryoma Hoshi the incinerator key. The next day, he introduces the motive: accomplices would be able to escape with the blackened in the situation that they won the trial, but wouldn't die alongside the blackened if they lost.

After a few days, Izuru Kamukura's body was discovered in the incinerator room, and the first class trial happened. The trial ended with Monokuma executing Ryoma, who was manipulated into being the blackened by Sou Hiyori.

Chapter 2:
Monokuma lead the students into the newly opened third floor, where they met six new participants. After searching the new floor, and finding nothing of specific importance, Monokuma introduced the second killing motive: that any killer would automatically win the class trial if a majority decision wasn't reached within 2 hours.

After a few days, Ayumu Fujimori's body was discovered in the pool, and in under two hours, the students found out the killer was Kirumi Tojo, assisted by Sou, who agreed to help just so he could betray her in the class trial.

Chapter 3:
On the new floor was Jotaro Kujo, who everyone decided they didn't like, including Monokuma. The new floor had a locked camera room, which couldn't be accessed by any means.

Monokuma introduced the Despair Disease, a disease that would alter the personality of whoever was infected by it. Everyone was infected by it, save for Kaede Akamatsu, Kanade Otonokoji, Aoi Asahina, and Sou Hiyori (who was revealed to be faking it.)

As a result of the motive, Kokichi Ouma and Reimu Hakurei's bodies were discovered in the music room, to which it was deduced that Reimu killed Kokichi, but Kanade killed Reimu afterwards, claiming it was because she didn't want her to feel the pain of getting executed, and that the cast wouldn't despair from seeing it.

During the class trial, Monokuma would object to Kanade, who claimed the paper found in Kokichi's hand was proof Reimu was strangling him, to which he questioned her previous logic where she claimed Reimu entered the room after Kokichi died.

Chapter 4:
The newest floor had Kai Satou on it, who revealed he was an assassin to Kanade, Aoi, and Hibiki Otonokoji. A morgue room was discovered, where they found the tanks couldn't be opened, and had dead participants in them. Monokuma gave a motive that the killer could escape with anyone of their choice if they won the class trial.

Days later, Jotaro's body was found locked in a spot in the morgue, and it was proven that Miu Iruma did the crime overnight, and injured herself to seem innocent. Because of a catch in the motive Monokuma never mentioned, Miu was executed alongside Rantaro Amami, who she intended to escape with, seeing the dangers of the killing game's participants.

Chapter 5:
Monokuma allowed Kanade to break into the camera room, giving her the condition that she wasn't allowed to mess with the cameras. Kanade and Kaede investigated the area, noticing a plaque that stated the rules Monokuma had to comply to; one of these rules was that he couldn't execute anyone falsely, to which Kaede shut Monokuma down and destroyed him. However, he was replaced with a new model.

The next day, Monokuma opened up the final floor, the Monokuma Factory. The floor was opened as a distraction so they wouldn't notice the final motive being given, Forbidden Actions. Each person with given an action they couldn't perform unless they wished to die. However, one person had a Reverse Action, that if they completed, would escape at the other's expense. Later that day, Monokuma told Kaede to go to Rantaro's room, and in there, he was found to be alive, and was only fake-executed in an attempt to the shatter the hopes of the remaining students.

Days later, Sou's "Head" was found hanging from a rope in a secret room, and the final class trial began. Rantaro was 'proven' as the killer, due to being in the only possible position needed to fake the body's existence. He was then executed.

Chapter 6:
After several attempts to vain to retrieve the headmaster's key, the students recover footage of Sou's death, finding out he had stabbed himself instead of Rantaro doing it. Monokuma, upon seeing this, executed himself, giving the remaining students the key they needed to unlock every room in the school.

A doll of Monokuma, one who would barely speak full sentences and had no personality, was his replacement, and so the investigation went on.

At the trial, after the students realized they were only clones of their former selves, being in the 400th loop of the killing game, Monokuma revealed the doll to act just as himself, reveling in the despair and realization that this may also very well be another cycle in vain.

The students decided Kanade was the mastermind, but falsely voted, sending them all off to their deaths in a mass execution, which was stopped by the Original Survivor of the first killing game, Rantaro Amami.

The mastermind, the original Kanade set off a bomb in the school, and Monokuma, realizing he'd lost, gave Aoi the key to get out of the school, and was blown up along with the rest of the bunker, save for the cloning research room.

Prologue:
Monokuma introduces himself as a friendly Tour Guide to the other students, giving them the original set of rules, wishing them enjoyment on their seven days of paradise.

However, Monokuma would return, summoning the others to the hotel lobby. That's when he suddenly glitched into his headmaster form, and informed everyone of their trapped state, and how they have to kill each other to escape the island.

Chapter 1:
Monokuma would direct everyone's attention to the plaza the very next day, telling them all about the store, spa, and pool they had there. He would maintain a distance for most of the time, not seeing any reason to interject himself into their lives until Mikado Sannoji attempts to kill a Monobeast, where he has the Monobeast shoot him in the leg.

The day after, the Tour Guide Monokuma agreed to help everyone set up a concert for Ibuki Mioda and Sayaka Maizono. He also tells them that the Headmaster Monokuma planned to give them a motivation for murder.

This is confirmed when they're all called out to the plaza, where Monokuma informs them all that one of the people in their group was a traitor, who was set to kill someone. He gave them a sort of silver lining with the fact that if they found and killed them, they'd all be set free without a trial even occuring.

On the day of Mikado's body discovery after the concert, Monokuma had a class trial occur in a dome in the plaza. They deduced that Mikado killed himself to stop the execution of Ren Shirogane, after he attempted to kill him.

Reimu Hakurei
Reimu consistently fed Monokuma some of the food made for the other students, to which he happily complies with. This starts a noticable bias and goes to the point that Monokuma becomes depressed when she dies in Chapter 3. He even goes to the point of objecting to her being accused as the culprit by Kanade during the third trial.

Sou Hiyori
Monokuma frequently plays Go Fish with him, building some trust with him. He considers Sou as the only valuable student after chapter 3, and allows him a bit more leeway. He mainly likes him because he works away from the rest of the group, the ones he considers annoying.

However, once discovering Sou and Rantaro's plan, he begins to despise them, calling the two "a pair of useless greenies".

Kaede Akamatsu
They very much dislike each other, Monokuma hating her because of her blindly hopeful outlook, and Kaede hating him because he started the killing game. In chapter 5, he mocks Rantaro's supposed death to her face, causing her to destroy him.