One of the few, yet common, criticisms levied at the 2017 Made in Abyss television series was at animator Kou Yoshinari’s creature designs and animation. When Yoshinari was given creative control of how the creatures of the Abyss would be designed, he purposefully made them visually-jarring and otherworldly. They’re animated as an other, with blurred lines that distinguish them from sharply-detailed backgrounds of the Abyss itself.
Alongside the citizens of Orth and cave raiders of the Abyss, we as viewers know little about this gaping maw other than what the series tells us. The series’ visual direction makes us part-time travelers with Reg and Riko, and part-time voyeurs, watching them from a distance with a calculating eye (like the monsters, the Abyss which is a character all its own, or high-level cave raiders like Bondrewd who have eyes everywhere).
The monsters aren’t animated badly, they’re unnatural by design.
An interesting choice made by either Yoshinari’s direction or one of Made in Abyss‘ animators was that, at one point, Reg’s robot arm becomes equally blurry to the monster he is fighting. It happens early on in his and Riko’s journey, but for a moment, the animation style of Reg — a main character in the series — becomes identical to that of the monsters that populate the Abyss. At that time, I wrote:
The first layer’s silkfang is shown as perpetually blurry with a dark, thick outline that moves constantly, but Reg’s robot arm is given the same treatment when it grabs hold of the monster. This could be a simple animation necessity, but in Made in Abyss, it could always mean more.
Reg’s existence throughout the series was always a mystery, with Riko and viewers piecing together his backstory the further the two delved into the Abyss. He is likely a relic, but doesn’t appear in any of their compendiums or existing data. He was presumably sent by Lyza as a gift to her daughter Riko, but neither Riko nor Reg know why or where Reg came from. Like the Abyss, he isn’t known, yet Riko treats him as if he’s another cave raider and, for the most part, Reg is animated accordingly. Even when he uses his most powerful weapons during the scope of the series, he retains his clearly-animated form, delineating him from the monsters outside of this specific occasion.
In the sequel movie, Made in Abyss: Dawn of the Deep Soul, Reg becomes overloaded with power and loses his sense of self. During this time, he fights noted white whistle Bondrewd: Sovereign of the Dawn. Bondrewd’s villainous tendencies are painfully human — which make his machinations worse, not better — but he’s shown sharply in relief to Reg who fights like an animal or monster of the Abyss. Reg has the same blurry look and thick outlines of an Abyss monster while Bondrewd is clearly and precisely drawn. Not only does this momentarily align Reg with the monsters, but it tells us visually that Bondrewd is in complete control of his actions (which again, makes it worse, not better) regardless of how vile those may be.
As an aside, it’s worth noting that Kou Yoshinari is once again credited in Dawn of the Deep Soul, this time under “biological design” rather than monster design.