Hunter x Hunter - episode 56 - 09 Feb, 2001

Killua remembers that his father once was paid to kill a Phantom Troupe member: he succeeded but said it was too hard and advised his sons to stay away from them. Gon, Killua and Leorio spend four hours searching with no results, and Gon decides to get a loan of 100 million jenny for his Hunter License. Kurapika and Uvogin fight with the latter going from 20% of his strength to 50% and finally to 100%, yet Kurapika has the upper hand due to a deadly oath and finally kills him. (Source: Wikipedia) Yorknew City arc/Phantom Troupe arc: (12/26)