All great men leave behind a tale, but someone should probably write it down first.
But for all of their amazing feats, who knows the complete truth about any of them? For every battle they’ve faced, every land they’ve seen, every deed they’ve done, the only ones who know what really happened are those who were there: the Straw Hats themselves and their allies at the time. For the rest of the world, though, the media and the government distort the truth to either make the Straw Hats look like villains or to make themselves look like heroes, such as when they claimed that Smoker defeated Crocodile in place of Luffy.
But the government can only distort the truth on matters they know about. Events that they know nothing of, such as Luffy defeating Kuro or going to Skypiea, go completely unreported, despite being some of the most outlandish or fascinating of the Straw Hats’ adventures.
Since Luffy has declared war on the World Government, it seems like a safe bet that he’s going to, one way or another, crush the system as a whole and leave the world to repair itself in the wake of his path of destruction. As a consequence of that, all of the World Government’s lies are bound to come to light. Alternatively, though, the exposition of the World Government’s lies might tie into their downfall. To that end, the best way to spread the tales of the Straw Hat Crew and possibly the True History found on the Poneglyphs may be to have someone within the Straw Hats keeping a record of everything with the intention of future publication. On most pirate crews, this sort of thing falls on the shoulders of the chronicler.
Typically, the events of a crew’s journey are kept by the captain in the Captain’s Log, so the captain often doubles as the chronicler. In the Straw Hats’ case, though, I have difficulty believing that Luffy would ever sit down to record the outlandish events he’s experienced, much less in a way that’s understandable or even legible to the common reader.
A better option may be Usopp, who has a natural gift for storytelling.
My personal interpretation has always been that Robin would make the perfect chronicler.
Since we’ve never seen any of the Straw Hats take on the role of chronicler, we can assume that if they are to have one, it will be someone that they recruit in the future rather than someone currently on board who gets assigned to it later. Whoever it is, they must be good at gathering, retaining, and organizing information. As far as I know, no one in the series has been shown actually engaging in storytelling other than Usopp, so we’ll leave that criteria off.
Up to this point, I’ve suggested on a few occasions that if she were to be recruited, Tashigi might make a good chronicler. She’s very good at retaining information…
…and she’s been shown taking notes at least once for the sake of record keeping.
As far as keeping track of information goes, Tashigi seems like an excellent candidate, as this is likely all a part of her normal duties as a marine. However, her main focus in terms of information gathering and retention is on swords, not on people or events, so she may not have quite so easy of a time with chronicling the Straw Hats’ stories as we would like.
What we really need from a chronicler, though, is someone whose whole job is focused around information. Someone who can conduct background research, take comprehensive notes, retain what they learn, and apply it. Our ideal chronicler would likely be someone who has training as a secretary.
As far as I remember, only one character has acted as a secretary in any capacity across the entire series: Monet. As a secretary (and spy for Doflamingo), Monet is always working with information in one way or another. When the Straw Hats showed up on Punk Hazard, she immediately set out to gather information on them, even finding obscure details like their relationship with Law.
With such skill at information gathering, it would likely be a simple task for Monet to interview the Straw Hats to learn about their earlier adventures and sift through the lies and exaggerations to piece together a coherent truth.
Any time Monet wasn’t busy doing anything else, she could be seen with her nose buried in a book and a pen in her hand, taking notes on who knows what.
Seeing how neat her writing is, we can extrapolate that she is good at organizing information, possibly even with good diction along with page layout. If she were to compile the Straw Hats’ stories, she would likely be able to make them easy to understand for a general audience while still making an enjoyable tale.
We can also infer that she is likely good at retaining information, as she is very studious and thorough. She even demonstrated this by memorizing the Straw Hats’ epithets and bounties after only seeing them once.
Since she’d be experiencing events firsthand if she joined the Straw Hats, it would be extremely helpful for the chronicler to be able to memorize said events as they happened, as she wouldn’t need to rely on the conflicting accounts of her crewmates.
Most importantly, though, of everyone in One Piece, not a single character has been shown writing as often as Monet has, so while I would love for her to apply her apparent love of astronomy to the Straw Hats or use her wings to act as a scout, her true skill and passion seems to be centered around writing, so it would be a shame if whatever job she was assigned in the Straw Hat Crew didn’t allow her to put that skill to use.
I still think that she could do great things for the crew as an astronomer or a scout, but I firmly believe that a chronicler will be absolutely essential, at least for preserving the crew’s legacy, and who better to do that than someone who loves to write all day?
*Theory by Tokiro Oumaga