Leorio is initially introduced as a very selfish narcissist who places great emphasis on material wealth. Despite his assertions that he is only after money, he eventually reveals to Kurapika that he lost a close friend to a debilitating illness and this inspired him to become a doctor and earn money in order to help the sick and poor. He believes that all things in the world (lives, dreams, etc.) can be bought and that becoming a Hunter will provide him with the necessary funds for his medical education. In the Hunter Exam, Leorio meets Gon, Killua and Kurapika, the other three main characters of the series.
Some of the characters such as Killua near at the beginning of the story mistake Leorio for an old man, but he is actually a lot younger than he looks, being a teenager at the start of the series.
