Kai Kudou is the main protagonist of the story. His only family member is a weaker, younger sister who is said to have extremely powerful psychic powers. It is also believed that Kai has the same power but hides it. It is either he hasn't unlocked these powers yet or isn't aware of them. He's also extremely sensitive to sweets, to the point where even the mention or sight of it makes him uneasy.

(Source: Wikipedia)