Karma Akabane is a high school student of Orora High School. He was originally apart of Class 3-C until he decided to go into Class 3-E, only to go into 3-D after returning from the Underworld.
Karma is rather charismatic, and easy-going in most situations, often acting pretty impish and mischievous towards his friends. He keeps a calm head and cheeky nature, even in dire and deadly situations, though he would end up serious if pushed too far, put in an almost narcissistic behavior, finding enjoyment in humiliating his foes. He is well known for his violent and rebellious behavior amongst his school. Despite this, he holds a loyalty towards his friends, and will not fall to his enemies no matter what the case may be.
At the start of the series, Karma would usually look after himself, and not get too involved in matters he believed to not be his problem, only stepping up when he felt like it and nothing else. Though, he dropped this trait not too long after the finals, and after Korosensei gave him a pep talk about it.
Not too much is known about Karma Akabane as a child, though it is hinted that he spent most of his time alone, due to his parents being world travelers and as such not spending too much time with him.
Karma first appears as a 3-C student of Orora High School, teasing Nagisa by scaring him on the first day of school. He also soon became Blair's roommate once he caught her in bed with him, and agreed to let Blair stay with him after a short explanation. After showing her to Nagisa and Aladdin however, Karma refuses to go and help get Blair's home back, saying he didn't enjoy taking risks with his life on the line, and shrugs off the fact that Blair will stay with him until he will.
When the houndour showed up to attack them, Karma took to the fight, and later joined Pinkie in luring the pack over to a clifface, succeeding in killing most of them with the exception of one.
When told Nagisa was absent after the Midterms, Karma began to suspect some ulterior motives involved, so he took it on himself to go off and find him, only to find him doing a spying mission at the 3-E Building. Not too long after figuring it out, he followed Nagisa back to Gakuho Asano, and suggested to take his place and drop to 3-E, saying how he wanted to dump him there ever since he showed up. He only did that though because he was curious over Korosensei, and wanted to mess with him, and was confident that he'll get back to the main building once the finals come around. During the weekend following, he helped in studying Nagisa's Demon Sense, and Pinkie's "Pinkie Sense" by giving them a test over in the forest by the 3-E building.
He arrived to the 3-E building following, and quickly started to enjoy the E class when he managed to hurt the teacher before anyone else. He continued his tricks throughout the day, getting to know some of the students of 3-E, most notably Rio Nakamura, until he came across a Banette. He was the one who confronted the demon with one of Korosensei's blades, only to find that they didn't work, and nearly got killed until he retrieved his Miracle Sword, and killed it instantly. Later on, Envy came to his house disguised as Nagisa, and got Karma to go out after a demon. Once they arrived though, Karma figured him out, asking Envy since when did they go after demons deliberately. This sparked a fight between him and Envy, Karma nearly getting killed by the Homunculus, until he was saved by Korosensei. Karma stabbed his sword into Envy, and left him there.
During finals, he and his friends were called into Gakuho's office, only to find out that Sombra had possessed him, only keeping back when Sombra warned him of being charged for Gakuho's murder if he did so. Once the meeting was done, Karma found he was stuck in 3-E still after he saw his test scores weren't enough, prompting a pep talk from Korosensei.
Amongst the group, Karma was the one who happily accepted Pinkie's offer to go to England, thinking that he might be able to run into his parents while there. His vacation in England went fairly well at the start, and once they got invited to the Phantomhive Manor, he took it in stride and suggested to go and see what'll happen. Upon noticing that Ciel Phantomhive had been kidnapped, Karma at first suggested to just leave it, but changed his mind once fully thinking on Korosensei's words, and decided to go and rescue him. He and the others made it to Ciel, and Karma decided to drive the boss away, who later turned out to be Envy. He gleefully left Envy after he shoved mustard and wasabi up his nose.
Sometime later, after finding that Twilight had left them, he suspected that the letter could be red herring, but agreed to wait until the end of the day, only to find his suspicions correct. He helped Nagisa look for Twilight for the next few days, up to the Royal Ball. While there, he tried to find Envy and Lust, only to end up in a trap by said Homunculus and nearly getting killed from it. Sometime after this, he found that Nagisa had finally found Twilight, but once she got back, he confronted her and made her tell them about Hellgar, him coming up with a plan to ambush him when he would come for her.
The queen called him and his friends later on, and he informed her about the Homunculus, Envy in particular with his disguise ability, as he was assigned by her to join her troops on patrol. Karma though became bored after a while, saying how nothing had happened yet, but quickly spurred into action once Hellgar and his pack showed up, fighting most of the houndours. When he got launched back in a firewall by Hellgar, Karma followed Nagisa's plan and cut down a pillar to be used as a bridge for the group before they had to evacuate due to the crumbling building and oncoming fire. Despite the carnage, he barely got hurt, and recovered quickly afterwards.
Karma agreed along with the others to go off with Ciel Phantomhive to Amestris on their task for Central. During the train ride up though, the group ended up attacked by Lust and Gluttony, but before he could fight, Edward Elric send them on their way. He arrived to Central soon after, and he informed King Bradley about the situation with the Demons, and even showed him evidence of Envy's spying within Central. He tried to figure out envy during his stay, and eventually aided the others in capturing him.
During the Pluton attack, Karma helped in building up and taking down Pluton, calling the signal for the tanks to fire at him.
Karma arrived back home with the others, and took up some practice in his swordsmanship with Edward Elric once he got into his school.
As he was doing this, he found that King Bradley was going to stay in Tokyo for a while, and so he went to the capitol with the intension of having him take him on as a apprentice, to which Bradley eventually agreed too only for as long as he stays. Eventually Nagisa gave him the warning of him possibly getting killed by a demon during one of his training sessions in a duel, and after being told all of them, Karma keeping personal guard over Heine Wittgenstein throughout the day up to Gakuho Asano's attack. Karma's turn came as Nagisa had described, and soon he was found by a Crow Tengu, but instead of avoiding the fight, Karma confronted him and tied his sword to his hands, believing that he will be fine so long as his sword stayed in his hand, yet his fate was defied when Alphonse Elric saved him from the killer blow. The attack resulted in him at the hospital alongside Edward, recovering for a few days for his injuries.
Karma met Nagisa during Nagisa's years at Orora High School, and he and Nagisa became good friends in a short amount of time, though he does like to tease Nagisa on more than one occasion, be it either being Twilight's boyfriend or for him looking like a girl.
Blair is Karma's demonic roommate. Karma took a liking to her right away, even after finding her in bed with him, and usually enjoys Blair's company throughout their adventures together.
Asano seemed to have a sort of superior mood towards Gakuho. He heard about Gakuho's treatment to some bullies in the past, and apparently Gakuho wanted to dump him into 3-E on his own terms rather than on Karma's terms.