Initially, Killua is introduced as a character who seems similar to Gon; cheeky, cheerful, and full of mischievous ideas. He is also one of the most quick-thinking characters in the series. He is confident in his own abilities, often being humble about it. However, his ruthlessness and aptitude in killing shows the other side of him — deadly, violent, and bloodthirsty. He has short, fluffy, white hair with large, blue eyes.