“You should have more confidence. You are progressing at an incredible pace. You're a one-in-a-hundred-thousand talent. However, those two are one-in-ten-million talents.”
-Wing, to Zushi, Hunter x Hunter 2011, episode 35
In traditional shounen fashion, Hunter x Hunter's setup necessitates power ups for its leads, logically followed by more power-ups. Protagonist Gon Freecss has set out to find the father who abandoned him as a child to pursue his own interests as a hunter. His father is one of the most powerful and elusive hunters in existence, therefore requiring Gon to increasingly become stronger. Gon's first test is to pass the rigorous Hunter Exam, the latter portion of which teaches Gon to use a power called Nen.
Hunter x Hunter follows the standard narrative, providing ample mooks for Gon and best friend Killua Zoldyck to cut their Nen teeth on. It is in their Nen training that the traditional problem of the shounen power formula rears its ugly head. When characters become stronger, they must be balanced with more powerful adversaries. Creators run the risk of their protagonists becoming so overpowered that the strength of all others in the series is undermined.
How does Hunter x Hunter portray how powerful Gon and Killua have become without sacrificing the audience's suspension of disbelief, or worse, the viewers' emotional investment in Gon and Killua's improvement?
The answer comes in the pint-sized martial arts student, Zushi.
Zushi first encounters Gon and Killua en route to floor 50 of Heaven's Arena. All three boys are attempting to climb up to train their fighting abilities. It is conveniently through Zushi that the two best friends are introduced to Nen teacher Wing. Throughout their training with Wing, Zushi nips at Gon and Killua's heels, quickly realizing that the two have far more natural talent than Zushi ever will. What it takes him months to learn, Gon and Killua master in mere hours.
The test that measures their Nen ability is easily passed by both Gon and Killua, where Zushi is told by Wing to train for a few more weeks. It is obvious that Wing believes that Zushi has potential; however, it pales in comparison to that of Gon and Killua. As Wing says to Zushi, they are one-in-ten-million talents, where Zushi is only one-in-ten-thousand. Here, Hunter x Hunter illustrates Gon and Killua's prospective power while framing their ascension to such power in a human light. The floor 200 “newbie hunters” are fodder for Gon and Killua's growth. Zushi acts as a benchmark for how far they could go. Gon's fight with Hisoka shows the immense gap that still exists.
Throughout his training with Gon and Killua, Zushi suffers from several crises of confidence, spurred on by none other than his own master, Wing. Zushi is easily able to compare himself to the two prodigies and realize that they are naturally more talented. At one point in their collective training, he asks Gon and Killua to stop, under the guise of needing rest, lest he lose confidence. Killua picks up on this and they cease training for that day, sparing Zushi's feelings so he can come back more determined instead of less.
However, as a Nen user, Zushi can still feel the presence of others relatively well. Specifically, he is in tune with Wing's emotional state. When Wing becomes both excited and afraid at the prospect of training Gon and Killua, Zushi can feel it. He can feel that his master is excited to teach someone other than himself. He can briefly feel that Wing is more thrilled to teach them than he is to teach Zushi. To his credit, Zushi says nothing. There are hints of discouragement in his demeanor - the aforementioned request to stop training, his assertion that being told that he is a one-in-a-hundred-thousand talent means nothing if Gon and Killua are two-in-ten-million - but in the end, Zushi chooses to keep moving forward, assuring Wing that he will catch up one day.
“I'm glad to have met you! You have set a worthy mark for me to pass.”
-Zushi to Gon and Killua, Hunter x Hunter 2011, episode 36
It is doubtful that Zushi will ever catch up to Gon or Killua. Killua echoes these sentiments while Gon, ever cheerful, states that he looks forward to that day. When Zushi catches up to where Gon and Killua are at the end of Heaven's Arena, they will have advanced beyond what Zushi may be capable of. Although Zushi cheerfully waves goodbye to the two prodigies, there is a lingering sense that he will never stand next to Gon or Killua as an equal. They are leads in this series, where Zushi is not.