Near the end of Hunter x Hunter's Chimera Ant arc, Gon finally confronted the powerful Neferpitou. After learning that his beloved friend and father figure Kite was already dead, Gon’s rage spiraled out of control. He made a Nen contract that enabled him to defeat Pitou. However, the price paid for this power was Gon's potential: he gave up his future for the here and now.
Source：https://www.cbr.com/did-gon-get-his-nen-back/
