The final member of the Generation of Miracles, he stood at their head as captain, leading their team to uncontested victory during the three years he played for Teikou Middle School.
Thus, when it became clear that Aomine would not be able to participate in the final rounds of the inter-high school championship, he also withheld himself from playing and demanded Murasakibara do the same, wanting to make the games at least a little interesting. He upholds an extreme “winner-take-all” philosophy, believing that victors are granted absolution in all things, while losers are denied everything. He claims never to have lost at anything, and as such he believes himself right in all things; he grows violent towards those who thus defy him, attempting to stab Kagami with a pair of scissors when the latter refused to leave even when told to do so. Respected and feared by the Generation of Miracles, they assemble as he demands, and can’t help but heed his words.
It was later revealed in the Teikou arc that Akashi used to be a normal individual; he has a calm demeanor and can be a very good leader. But Midorima sensed that at some times, Akashi could change to a completely different person: colder and more ruthless, but only in a very short period of time, and then will return back to normal.
Then soon the members of GoM’s talents started to blossom until they had become too strong to enjoy playing basketball. At some point, Murasakibara questioned Akashi’s strength, and doubting if Akashi was really stronger than him. Akashi challenged Murasakibara to a one-on-one match to prove who was actually stronger.
But Akashi was overwhelmed: he didn’t realize Murasakibara had gone this strong. One more point to his loss, his “other side,” which Midorima had come to notice, awakened. He then beat Murasakibara easily, and thus confirmed his position as the captain once again. Then he explained that he actually had had two personalities all along, those personalities merely traded places.
Ever since that match, Akashi was never the same. He grew to be the absolute ruler of the team, and believed that nothing matters more than winning.
What’s scarier is, aside of the Emperor Eye, Akashi seems to own another power, which was meant to “blossom naturally” along with the other GoM members when they were still in Teikou, but that another power was interrupted when Akashi became the “different Akashi.” So, his ‘old Akashi’s power still remained unknown, but this was noted by Seirin members as they proceed to face Rakuzan in the finals.