Seijūrō Akashi (赤司 征十郎 Akashi Seijūrō) is the captain of Generation of Miracles. He is the only person that the Generation of Miracles knuckles under. He is now the point guard and captain of Rakuzan High and is competing in the Winter Cup. Akashi now serves as the main antagonist in the story. 

Akashi has a rather small stature for someone who has captained the Generation of Miracles, as noted by Furihata, at only 173 cm tall, making him the shortest out of the Generation of Miracles. He has spiky red hair, large eyes with vertical pupils. His hair was worn with longer bangs in Junior High school and during the events preceding the Winter Cup. However at the beginning of the Winter Cup he cut them with Shintarō Midorima's scissors. Color pages have shown that Akashi has heterochromatic eyes, with his right eye being red and his left being yellow/orange. It was shown in a recent chapter that back in Junior High school, Akashi's eyes were both red. The change in colour occured in Junior High school when the initial conflict between the Generation of Miracles occurs. It can be noted that after his eyes changed, his personality also becomes much colder. He wears the white and light blue Rakuzan jersey with the number 4.

Akashi's appearance was not revealed for a long time. The times he appeared or was mentioned, only the lower part of his face or the back of his head was shown. It wasn't until Winter Cup that his full appearance was revealed. 

Source: http://kurokonobasuke.wikia.com/wiki/Seij%C5%ABr%C5%8D_Akashi

Trivia: According to the CHARACTERS BIBLE:

    Akashi's alternative job choice is to be a professional shogi player.
    His hobbies are Shogi, Go(Wei-qi), and International Chess.
    His specialty is horse riding.
    His favorite food is tofu soup.
    His motto is "Quick and decisive".
    He hates disobedient dogs because they don't listen to him.
    His type of girl are girls who have dignity. 
    Has no particular weaknesses.