Higashi Kiyoshi is a 15-year-old boy who lost his birth parents to a fire when he was four. Three people came to the orphanage a month after to adopt him; a mother, a father, and a son. The mother was a kind pretty woman who cared for him like her biological son, and the father was a hardworking businessman who he admired and sought to be like. His brother was five at the time. He loved to play basketball and was very tall. He was the reason Kiyoshi started to play the sport.
At first, he was bad at the sport but his older brother was exceptional. At 13, he was 6'2". Kiyoshi, on the other hand, was 5'2" at thirteen. Kiyoshi always compared himself to his brother and he would always be on the worse side. His brother outclassed him at everything and made him hate himself. At four years old, Kiyoshi loved his brother because he was closest to him, but his brother's constant outshining made him not want to be near him. Kiyoshi dropped basketball when he was almost 14. That way, Kiyoshi could stop comparing himself to his much better brother.
His brother continuously tried to get him back into the sport so that the could be on the same high school team, but Kiyoshi didn't want to. He didn't want to be in a position where he could compare himself to his brother so he even purposely failed the entrance exams to his school and went to a no-name high school without a basketball team. When he felt even the slightest urge to play basketball, he would suppress his feelings and focus on his studies so that he could think about something else.
One day, he went to pick his brother up from training a bit early and witnessed the team's strength. He saw a bunch of passes that a particular player had made and instantly fell in love with the playing style. From that day on, he went to his brother's school every day about thirty minutes early just to watch him play, and one day, he attempted the playing style. It felt natural to Kiyoshi, and it was immediately learnt by him. The mystery player's name was Kuroko, and his brother was Kiyoshi Teppei.
Afterwards, he joined the HBI as a player and got back into basketball. He also joined so that he could play against his brother and his mystery player.