Shuya Arisada is the president of the student council, he is a very confident person who was also a former Princess one year prior to the beginning of the story. He is a very good leader and often comes up with fool-proof plans which benefit him and the rest of the student council. He can also be very intimidating to talk with and in effect people often go along with his plans regardless.
Arisada is a very manipulative person. He was the first person to call Akira Sakamoto "Sakamoto-sama", thus beginning and encouraging the trend (to the younger Sakamoto's dismay). He also pushed and forced Akira to take over as president for the next year.
Arisada himself has admitted to loving power and wanting to be a rich entrepreneur.