Tite Kubo's Bleach may have had a truncated end in both the anime and manga releases of the series, but there's a reason that it's still one of the most popular series to ever come out of Shueisha's Weekly Shonen Jump. It may not still be continuing in some fashion like its fellow Big 3 compatriots, but it really doesn't need to. It left a huge impact on fans with its characters, stories, and most importantly, its fights. But it can be hard to choose which fight stands above the others.
While there are plenty of cool fights to pick from, there's really only one that shook the franchise's status quo. There's one so memorable not because it's a flashy affair, or particularly brutal, but its pure shonen action and storytelling condensed into a single fight. The Ryoka Invasion arc had its fair share of highlights, but Ichigo Kurosaki vs. Kenpachi Zaraki was, without a doubt, the best.
Any good shonen story will grow see its main character overcome an increasingly stronger set of rivals as they grow in power, but Bleach's early days were a great example of how to do this right. Before the series got inflated with multiple wild power scales and conflicting factions raising the power scales even higher than one could feasibly keep track of, Ichigo had a concise goal of becoming a substitute shinigami. Then the series tested this even further when he realized just how little he actually grasped about life as a whole.
Throughout this first arc, Ichigo believed he was overcoming a set of challenges, but he still believed he would have the ability to overcome anything. This changed when he met the various captains of the Soul Society when saving Rukia, and none had a bigger impact than Kenpachi. Unlike his previous foes, Ichigo wasn't fighting a monster. Kenpachi had a pride, and more importantly, a soul.
Though he was monstrous, Kenpachi had a pure and admittedly noble drive to fight. Unlike Byakuya he wasn't fighting for what he believed was right, he was fighting for the pure enjoyment of it. This was something Ichigo had never seen, or felt as a disconnected kid floating through high school, and this was his first confrontation with the "real world." Having Ichigo's most powerful attacks do nothing to Kenpachi showed him just how "hollow" his life really was.
Here was someone who wasn't standing on some platform above him, or lorded over him, but instead looking at Ichigo straight in the eyes and directly called out just how little Ichigo really had believed in to that point. He had just been going through the motions up until that point, and fighting Hollows just because. Even saving Rukia was just something he was doing, but facing against Kenpachi -- a person who was finely honed into his own ideals -- helped him become stronger.
This fight isn't about the flash. Sure Kenpachi has raw power, but neither of the two were fighting for grander things in that moment. It was Shonen's rawest emotions distilled into a single fight, and when the two wounded one another fans gained a new respect for each of these fighters. Ichigo had no choice but to lay himself bare in front of such an unhinged, unrelenting, and idealistic individual, and changed for the better because of it. Then of course there are just tons of fun dialogue moments back and forth during all of this as well! It really is Bleach's best fight.