This year I watched a number of shows where I've also read the manga version (either before or after the show aired). One of the interesting things I noticed about the anime versions is how they rearranged and adjusted early elements of the manga, and how this changed the feel of the story being told from one media to the other. To make this concrete, I'm going to talk about three shows (and there will be some spoilers).

The most straightforward to talk about is Land of the Lustrous. As part of an interview available on Sakugablog, director Takahiko Kyougoku explicitly discussed how some manga elements were restructured to give us more focus on the main character so we'd know who it was:

To go into more detail, we took steps like giving the main character more close-up shots, or having them intentionally repeat important lines. It may not seem like much, but when you watch it, you can tell which character had the most presence and what their goals are. [...]

What doesn't get mentioned in this interview is that the anime also completely omits a big infodump that happens within the first few pages of the manga, when Kongo tells Phos to recite the history of the setting as the gems have been taught it; this exposition includes both information we only heard later in the show and some that we still haven't. This leads to a restructuring of the conversation between Kongo and Phos where Kongo gives Phos their job.

Next is Made in Abyss. As mentioned in this interview with the mangaka and the director, the early portions of the show are revised from the manga for various reasons (including that the mangaka explicitly asked for the first part of the story to be 'brushed up'). As in Land of the Lustrous, the MiA manga starts with an infodump about the nature of the Abyss. It then goes in to a relatively long lead-in sequence before Riko and her classmates head into the shallow end of the first layer of the Abyss as part of their training, which is where the first episode of the anime starts.

In Made in Abyss, the change from the manga to the anime does more than cut out some material and tighten the story up; to a certain extent it changes our view of Riko's character. The manga opens with Riko boasting and making wild theories up, then her classmates cutting her down to size and being dismissive, and it goes on somewhat in this line. In the anime, we pretty much start with the heroic and active Riko who throws herself into the line of danger in order to save a classmate from an unexpected menace. Manga Riko comes across as someone with rather more significant feet of clay than the anime version, someone who somewhat stumbles into things rather than throws herself bravely in.

(As a result of this shift from the manga to the anime, I'm glad I saw the anime first before I peeked at the manga. Manga Riko is a somewhat less attractive character than anime Riko, since some of her flaws are more front and center and more emphasized.)

The rearrangements in both of these shows have been made primarily for structural reasons; they've been done to show us who to focus on and tighten up the story, partly because what works and is seen as necessary in manga doesn't necessarily work in anime. Their effects on the story itself are secondary or incidental, although I suspect that at least Made in Abyss is conscious of them. This brings me to my final example, The Ancient Magus' Bride.

In The Ancient Magus' Bride, unlike the first two works, the rearrangement isn't in the form of chopping out early manga material; instead it's the other way around. The manga version of AMB starts with a very cold open, where the first panel is Chise on stage in chains, being auctioned off as an implied slave. Only somewhat later do we find out that Chise had more or less voluntarily put herself in this situation instead of committing suicide. In the anime, the show opens with Chise explicitly agreeing to all of this; it is immediately front and center both that Chise is in an extremely nihilistic and bad mental space and that this is voluntary on her part. The story effect is to remove a certain amount of the initial shock from the manga and tone things down and make them nicer in general. More is explicit and explained, and as a result the whole affair comes across as more sad and less shocking and horrifying, at least to me.

With that said, I suspect that part of the rearrangement was driven by the structural mechanics of storytelling in manga versus anime. The manga version of Ancient Magus' Bride gives us the background of Chise's situation in a series of flashback panels that are intercut when present-day dialog and events trigger Chise's traumatic memories. This fluid intercutting between past and present is harder and less natural to do in an anime, and also not as clear. With manga's variable-speed pacing, readers can slow down to take in the flashback panels; what's going on is clear to us even though the panels themselves don't take up much room in the manga's first chapter (probably about a page and a half in total, spread across several separate flashbacks and specific incidents in Chise's past). I'm pretty confident that a good direct translation into animated form would take a lot more time, and so doing the whole background as a more or less linear sequence at the start of the first episode takes up less time and may well be clearer.

(This is part of the 12 Days of Anime for 2017.)