First and foremost we’ve got to remind ourselves that the point of this arc (and saga) is to establish Luffy and co. as formidable pirates with Luffy perhaps even surpassing the Yonko title to become a “Great Pirate”.
But more or equally as important, it’s meant to be the beginning of the end. In the bigger context of the story the trigger in this case the story to start blowing its whistle towards the end would be the return of Joy Boy, World Government’s nemesis.
We’ve got to remember that unlike any other villain , Kaido is an outlier in the sense that a lot of his character motivations (mainly involving Joy Boy) so far seem to be heavily tied with the current events involving Luffy, developments brewing a storm that will throw us into the finale of the series.
When you keep all of the above in mind, you’ll realize how Kaido astronomically trumps any other arc antagonist we have faced so far. So it’s wrong to put him under the monolith that is “villains don’t get more than a few pages of flashback anyway”.
Caveat – I’ll try and expand on everything that has been alluded towards Kaido’s character so far. That doesn’t mean that everything I say has to be explained by the story. But a lot of these points are inherently connected to the thought process in my preface.
1. Joy Boy, laughing and having fun
Perhaps the biggest one. By virtue of Wano’s placement right before the Final Saga, Kaido serves the purpose of introduce us to all the how? when? and where’s? of the moniker/name of Joy Boy/Nika.
This has already been alluded towards through these panels and points in the story:
Implication that defeating Kaido/liberating Wano marks the return of Joyboy
For the panel below I highly suggest all of you to check this tweet from Sandman (who’s a Japanese native) –
Uniquely structured dialogue out of the many other “laugh” and “fun” referencing panels
The panel above plays out in a way similar to Luffy and Roger’s “and then I’ll be…..!!!” where Oda is intentionally trying to omit a specific phrase/word. This guarantees that the dialogue holds a lot of significance. And this is just the tip of the iceberg when it comes to the dozens of fun/laugh/smile references we’ve had throughout this arc. All of these are associated with Nika’s entire schtick, which can only mean Kaido’s association with this Joy Boy business too.
Pre and post Wano invasion Kaido
You can see a jovial Kaido during King’s recollection of him in Punk Hazard some 30-35 years ago. It’s not conclusive enough to say that he used to think of himself as Joy Boy, but then you have to wonder what someone would strive to be when it concerns changing the entire world (knowing all that we do about him and Joy Boy so far).
Compare that to the stark contrast of his suicidal present self. Certainly not the mark of a man once brimming with life.
Time and time again Kaido has shown that he’s antithetical to what Nika (Joy Boy) is representative of. Of course this totally opposes Luffy’s ideals too, but the point to hammer in is viewing this in context to everything I’ve explained above in association to Kaido’s role in the story with Joy Boy.
One can infer that either Kaido had a skewed perception of what it meant to “become” Joy Boy or Kaido has acted the way he did all along to serve as a foil for the new Joy Boy (Luffy).
All of these points almost assure us of the fact that Kaido is going to at least serve as a means for us to know about the importance of introducing Joy Boy NOW of all times in the story.
Note before you jump the gun, this does not mean that Oda needs to spell out everything about Joy Boy’s legend. But we will certainly get the what? how? and where’s? of introducing this event in Wano, which in itself isn’t something to be omitted or glossed over.
It’s had its fair share of buildup by now and would make up a good chunk of Kaido’s flashback
This alone makes Kaido head and shoulders above any other villain Luffy has faced so far because Kaido serves a much much bigger purpose to the overarching story in this case.