The following Paragraph is taken from one of the JUMP GIGA Interviews where Togashi Yoshihiro, the creator of HunterXHunter and Masashi Kishimoto, the creator of Naruto were interviewed together.
Here Togashi talks about the huge amount of new characters which he has been adding in the manga specially since the beginning of the Dark Continent Arc.
Togashi Sensei: In the arc right now, I’m adding a ridiculous amount of characters while also stressing out about it. This is also instinct. [laughs]
JUMP GIGA: Can you really rely on instinct?
Togashi Sensei: Before you get to that stage, you obviously need to rely on an internal manual or a set of rules you’ve created.
But it’s hard for me to stay within those boundaries. It’s not so much about staying within my rules or not— I just like advancing the story in directions that I cannot predict.
JUMP GIGA: You want to break even your own rules?
Kishimoto Sensei: You have that self—destructive side to you. Like you know going that way is dangerous, but you can’t help it.
Togashi Sensei: That’s why this time I just simply increased the number of characters by a ton to see what would happen.
Kishimoto Sensei: That makes drawing the chapter so much harder…
Togashi Sensei: There are a lot of artists who have done it in the past—Oda sensei, for example.
I just figured if I could do it on purpose and not ruin things, it would make for an interesting story.
So getting back to the stage you create that allows you to rely on instinct, what matters is all the media you‘ve been exposed to, whether it be manga or novels.
By reading so many classic works and also bad ones, you can better arrange previously used ideas.
You just have more options. And this isn’t just with the story— I believe it also helps with character creation.
Hunter × Hunter (Japanese: ハンター×ハンター Hepburn: Hantā Hantā, abbreviated: HxH) is a Japanese manga series written and illustrated by Yoshihiro Togashi. It has been serialized in Weekly Shōnen Jump magazine since March 3, 1998, although the manga has frequently gone on extended hiatuses since 2006. As of October 2018, 380 chapters have been collected into 36 volumes by Shueisha. The story focuses on a young boy named Gon Freecss, who discovers that his father, who he was told was dead, is actually alive and a world-renowned Hunter, a licensed profession for those who specialize in fantastic pursuits such as locating rare or unidentified animal species, treasure hunting, surveying unexplored enclaves, or hunting down lawless individuals. Despite being abandoned by his father, Gon departs upon a journey to follow in his footsteps, pass the rigorous Hunter Examination, and eventually find his father. Along the way, Gon meets various other Hunters and also encounters the paranormal. The original inspiration for the manga came from Togashi’s own collecting hobby.