One thing should be made clear up front about this 13 episode “Netflix Original” production: it was produced by Polygon Pictures, the same studio which produced Knights of Sidonia, and uses the same kind of CG animation style. Hence if you were turned off by the animation in that one then expect the same kind of reaction in this one.

If that doesn't bother you (or doesn't bother you enough to interfere with the series' other merits) then you will find this adaptation of Gamon Sakurai's manga to be a dark, violent tale which is rarely subtle about portraying a sharply negative view of human nature. While the story does actually have some good souls in it – the longtime friend who rescues Kei at the beginning, an old woman who helps him out much later on – it mostly explores the worst side of humanity. It opens with scenes of child soldiers in Africa, randomly features two guys who have kidnapped a teenage girl with the intent of selling her off as a sex slave, includes criminals who traffic in human organs, and assumes that scientists are amoral enough that they would have no problem repeatedly killing Ajin as part of lab experiments. (In fact, they even go a step farther and sell Ajin off to companies for testing purposes, making a fortune in the process.) Basically, an Ajin who gets caught is condemned to a horrible existence, which is why Tosaka's Ajin assistant Shimomura is very, very loyal: her being on the right side of the experimenter's glass is entirely dependent on Tosaka keeping her secret. That may contribute to why Sato is ultimately unconcerned about collateral damage, although he is not above subjecting even an ally to torture to make a point and late episodes show that he is also a thrill-seeker who loves a fierce challenge, whether it be in video games or real-life. (And yes, the analogy between starting over again after dying in a video game and how an Ajin's immortality works is made, though subtly so.)

That general negative view of humanity doesn't exclude main protagonist Kei, either. Although he is occasionally helpful and considerate, some of his behavior borders on – if not outright crosses the line into – psychopathy. He doesn't appear to want to be a bad person but does struggle with empathy, something that his hospitalized sister has long been able to sense but cannot put properly into words (she just calls him a jerk), and some of his behavior is decidedly cold and calculating. When he eventually comes to oppose Sato's terroristic bent, it is because Sato's actions bring trouble upon him, not because he finds Sato's actions morally wrong. The effectiveness of this portrayal is debatable, as the writing seems uncertain how far it wants to go with Kei's antisocial behavior and clearly doesn't want to make him out to be a truly bad guy.

That is part of the reason why the series works better if thought of as a sort of rogue's gallery. Sato can thoroughly charm an audience even though he is also a ruthless and dangerous man. He also never lacks for bad-ass action antics despite looking like he's probably at least in his 50s. Tosaka's countermoves and own pressing concerns about his security in his position can also make him interesting, though less so. Sadly, not enough is done with Shimomura, but at least she doesn't fall victim to the series' bad tendency to use up and discard side characters.

And then, of course, there is the supernatural action aspect, which is what really powers the series. Ajin don't regenerate from normal injuries; they simply recover completely once dead. That means that Ajin cannot be killed permanently but can be incapacitated as long as they are not lethally harmed. Hence it's actually in a badly-wounded Ajin's best interest to commit suicide, which gives action scenes involving them, even when they're using ordinary weapons, a kind of disconcerting intensity. The story is thoughtful in how it examines this ability, too, as it shows one Ajin who has a weak leg due to a genetic defect who retains that defect upon regenerating, which implies that Ajin have a set physical state that they default to. Since Ajin regrow body parts which become far detached from their largest intact body part, the show even theorizes that death for an Ajin could technically happen if the Ajin is decapitated and the head immediately carried away, as what grows back to replace the head might not reform the Ajin's consciousness and soul. Would that be a different person? Would it be a zombie? Or would the soul transfer? It's an interesting philosophical and physiological question.

The true excitement, though, often comes from the “black ghosts” (or IBMs, as they are later called), which some Ajin can manifest. They look like shadowy, blackened, misshapen mummy wrappings with nothing inside and can usually only be seen by Ajin. Action scenes sizzle when they are on the screen, whether they are wreaking bloody mayhem against opponents who cannot see them or going head-to-head (sometimes literally!) with their own kind. The writing also puts a fair amount of effort into defining how they work, although Kei is, of course, able to bend the rules on that by the series' end.

The actual animation effort is trickier to evaluate. Some viewers seem really bothered by the unnatural feel to this animation style, and animation of background characters does seem a little stiff and repetitive. (The same female background character is used in two disparate scenes, for instance.) Still, Polygon does get credit for its level of detail, such as showing background characters receding when a street scene switches to a different angle. The production effort also goes out of its way to fully animate even innocuous movements like body language and casually idiosyncratic gestures, which makes me wonder if some of the problem might actually be the texturing. For all of the series' efforts to make the movements seem lifelike, the characters still have an artificial texture to their designs; the skin doesn't seem quite right and some of the rounding is unnatural, among other things. You don't get this same kind of effect with high-end CG productions like Pixar efforts in part because their designs are deliberately cartoonish, and thus there's no actual semblance of reality to contrast against. (Of course, the massively-higher budget is also a factor there.) As further evidence, the completely-unrealistic IBMs actually come off feeling smoother and more natural in their movements.

That aside, character designs are distinct and generally realistic except for Shimamura, whose large, more typically anime-styled eyes really stand out in a production where most other characters don't have them. (Significantly, she's also the only female Ajin we encounter in the series.) Characters and clothing do show wear and injuries (something not often seen with CG animation in anime) and the disintegrating/re-integrating effects commonly-seen in Knights of Sidonia, where little bits of matter drift off of a character/shape before coalescing again, also appear here. Also watch for some interesting messages on T-shirts worn by a couple of characters. Like with Sidonia, don't expect much for vivid colors; this could be a side effect of the animation process, although in this case it would make sense to keep the colors muted to prevent any suggestion of the story being cheery or happy. Graphic content is at an intense action/horror movie level, including torture scenes. Definitely not a title for the squeamish!

Driving the intensity of the work is a heavy, sometimes slightly overbearing musical score. Its mix of orchestration, electronica, rock guitar, and even occasionally vocals assures that dramatic scenes never lack for drama or that Kei's terror is shared with the audience. The rock sound of “Can You Sleep At Night?” makes for a suitable opener, while more mellow closer “How Close You Are,” sung by Kei's seiyuu Mamoru Miyano (you may have also heard him sing in the Uta no Prince Sama franchise, among others), is more notable for its visuals about silhouetted characters dying in various ways and flowery graphics springing from them to indicate their rejuvenation.

Netflix is offering both subbed and dubbed versions of the series, with audio available in Japanese, English, or French (all in 5.1, with non-5.1 options available for the latter two) and subtitles available in English, CC English, French, and German. The English dub is a strong effort anchored by veterans like Johnny Yong Bosch (as Kei) and Todd Haberkorn (as Tosaki) very fittingly-cast in key roles. English credits are not offered, but many of the smaller parts are also voices that will be familiar to long-time dub fans. I could not, however, place Sato, which is a shame because his gravelly English voice is easily the strongest performance; his voice actor finds exactly the right balance between being charming and menacing.

For all of its action elements and intriguing premise, the greatest strength of Ajin as an anime is actually its smooth pacing. It never lingers needlessly long on scenes but doesn't rush things, either, instead keeping events moving along at a steady, comfortable clip. As a result, watching several episodes in one sitting is highly recommended, as they can fly by. Unfortunately the series ends at a point that feels more like an episode break than a season or series stopping point. Several more episodes, at the least, will be needed to finish the story out properly, but as of the time of this writing there has been no indication about more coming. Still, overall the series is a solid, horror-tinged action thriller which can be pretty spectacular when at its best (such as in the terrorist sequence in episodes 11 and 12).