Cool Long Haired Gon 2023. The hunter × hunter manga series, created by yoshihiro togashi, features an extensive cast of characters. In addition to having long fur, this breed also has a wooly double coat designed to keep the dog warm even in freezing temperatures.

If he grew up to that age naturally, i doubt his hair would be that long. Killua, gon, kurapika and leorio. So, sometime after that, likely when he was placed in the hospital, his hair was cut.