Komaeda first comes off a polite and kind boy, but during the first trial he is revealed to be borderline insane. After showing off his true colors, he begins to ramble on about how hope is the most important thing in this world, and hope that is created from beating despair is the most amazing feeling that one could have. Komaeda also doesn't really care for his own life, in fact he encourages the other students to kill him as long as someone feels hope from it. He also considers himself worthless when compared to the other Super High School Level Students, claiming that his talent is pathetic and that he was born a talentless person who will never be considered anything special. Later, however, he finds his luck to be incredible and tells the other students to believe in themselves and Komaeda's own luck.
Ironically, despite his absolute belief in the concept of ultimate hope, it's heavily implied that he has no hope of his own. He has no family or friends, drifted aimlessly through life before arriving at Hope's Peak, doesn't believe he could ever amount to anything, and any chance he might have at actual happiness would be cancelled out by his cycle of good and bad luck.
Komaeda's life has always been a turn between 'good luck' and 'bad luck'. The earliest known occurance of this is when parents were killed before his very eyes after a meteor crashed into a hijacked airplane they had been on, letting him inherit all their fortune and become free to do whatever he wished, as he had no other relatives alive. After his parents' death, during middle school, Komaeda was kidnapped by a serial killer; although he was released after the police found him (it was implied that the killer let him go after they found out nobody would pay ransom), in the garbage bag the murderer kidnapped him in, Komaeda had discovered a lottery ticket. It was a winning one for three million yen; in that situation, the lottery ticket was the only good luck received. He has stated that his cycle of good and bad luck had worn him down to the point where he drifted through life without purpose, waiting to die.
At some point before the events of Super Dangan Ronpa 2, he presumably fell to despair along with everyone else.
Island Life of Mutual Killing
Komaeda begins off by acting polite and kind towards everyone, until the day Togami suggests the party. He pretends that he was unaware of the whole situation, and through his "Good Luck", he picks out the lot to be the one who cleans the old lodge. He makes use of this opportunity to set up and ensure that someone would die during the party, but was eventually discovered by Hanamura. During his plan when the lights went out, just as when he was about to target Togami, he gets pushed away by the latter and Togami gets killed by Hanamura, who was targeting Komaeda, instead.
He reveals his plans during the trial, causing everyone to start distrusting him. Komaeda was not present to investigate the new Island in Chapter 2, and the reason turned out to be that he was tied up by Souda and Nidai to avoid the same incident from happening again. After the news leaked out, people were assigned to provide him with his meals.
During the events of Chapter 2, he convinces Hinata to play the Twilight Syndrome game and helps him figure out that everything that happened in that game was going to happen. Because of this, Hinata, himself, and Nanami are able to deduce that Peko Pekoyama killed Mahiru Koizumi.
He relies on his exceptional luck to orchestrate his own death in Chapter 5 in an effort to expose the group's traitor. However, this fails; after it was determined in the trial that there was no real way to determine who killed him, the group of alive students voted off the traitor (who had outed themself), relying on Komaeda's luck to save themselves.