Wing

Wing is a Nen trainer whose main student is Zushi. He meets Gon and Killua at the Celestial Tower. Although in the beginning he refuses to train Gon and Killua, and even lies to them about Nen's purpose, he changes his mind when they reach the 200th floor, as he realizes they could die or be badly injured from nen "initiation". For the next several months he teaches them the basics of Nen, after which he announces they have passed the secret final requirement for being a Hunter. His teacher was Biscuit Kruger.