for making "remarkable achievements in a particular field"; they may then be upgraded to two stars for "holding an official position" and mentoring another Hunter up to single star level; and finally upgraded to three stars for "remarkable achievements in multiple fields". is the ability to control one's own life energy or aura, which is constantly emitted from them, knowingly or not. There are four basic Nen techniques: maintains the aura in the body, strengthening it for defense; shuts the aura flow off, useful for concealing one's presence and relieving fatigue; enables a user to produce more Nen; and is a person's specific use of Nen. Nen users are classified into six types based on their Hatsu abilities; strengthen and reinforce their natural physical abilities; project aura out of their bodies; control objects or living things; change the type or properties of their aura; create objects out of their aura; and have unique abilities that do not fall into the previous categories. A Nen user can enter into a where, by pledging to follow certain , their abilities are strengthened in relation to how strict they are. An example of this is Kurapika who, in order to have an unbreakable chain that will fully restrain members of the Phantom Troupe, offered his life, should he use it on anyone other than its members. Plot The story follows a young boy named Gon Freecss, who was told all his life that both his parents were dead. But when he learns from Kite, an apprentice of his father Ging Freecss, that he is still alive and has since become an accomplished Hunter, Gon leaves his home on to take the in order to become a Hunter like him. During the exam, Gon meets and befriends three of the other applicants: Kurapika, the last remaining member of the Kurta clan who wishes to become a Hunter in order to avenge his clan and recover their scarlet-glowing eyes that were plucked from their corpses by a band of thieves known as the Phantom Troupe; Leorio, a prospective physician who, in order to pay for medical school, desires the financial benefits that Hunters receive; and Killua Zoldyck, another twelve-year-old boy who has left his former life as a member of the world's most notorious assassin family. Among many other examinees, Gon continuously encounters Hisoka, a mysterious and deadly transmuter who takes an interest in him.