This is a major turning point where the Hunter Exam ends. It focuses on Gon confronting Illumi (Killua’s brother) after Killua is disqualified for murder. The themes are loyalty and Gon's refusal to accept a "win" that came at the cost of his friend’s freedom.
This covers the Chimera Ant Arc , specifically the birth of the King (Meruem) and the tragic evolution of the Chimera Ants. The themes here are much darker, exploring the line between humanity and monsters. This is a major turning point where the Hunter Exam ends
This takes place much earlier, during the Trick Tower phase of the Hunter Exam. It features a high-stakes psychological game of rock-paper-scissors between Leorio and the prisoner Leroute, focusing on themes of strategy, risk, and the group's dwindling time limit. This covers the Chimera Ant Arc , specifically
I can write an essay for you, but I need to know which version you are interested in: 1999 anime vs. 2011 anime)
The query looks like a link or search term for the "raw" (original Japanese) version of . Because of the different versions of the story (manga vs. 1999 anime vs. 2011 anime), "21" can refer to very different plot points.