The other storyline of HD is a little sparser, but the group of children being cloistered in a sterile lab setting with a fake outside that functions as a garden is reminiscent of Shinsekai Yori and Promised Neverland, though more so the former in the way the coming of age elements are handled, balanced with the simultaneous awakening of their unusual powers. Although these segments are important in the way they connect to the overall storyline, the proceedings are more detached, for we follow numerous characters who don't have much of an established personality, and I came to look at the group as a kind of "organism." There are a lot of ways in which the two storylines connect that are not immediately obvious, so it helps to pay close attention, but a second viewing will also prove more rewarding than numerous other series.
Information is slowly revealed about the devastated and dysfunctional world. However, with two co-occurring storylines that are equally vague and slow to reveal information, it can feel aimless at times. For Kiruko's group, they wander around in search of "Heaven," and they have no clues to go on other than hunches like, "Oh, wow, the water in this area is supposed to be 100% safe (derp) to drink, so they'd surely establish 'Heaven' there, right?" "Look at this bird symbol on my gun. Whoa, it's on the boxes, too!" Needless to say, it's more of a journey than a tightly plotted story, but the ambiguity makes the unraveling all the more enticing.
Only Kiruko and Maru are given the time to feel like full-fledged characters. Due to backstory reasons and the thematic focus of the author, Kiruko is the much more intriguing of the two. Maru is blander, and he's kind of your typical runt-like badass shonen main (FATAL DRIVU!!!) who can beat the hell out of everyone (except for bears). However, it's okay. There's a lot of chemistry to be found in their banter, and they sort of function as a comedy duo, for better or worse... On one hand, the two playing off of each other can be fun, but it depends on what draws you to the series.
If it's the enigmatic story and the post-apocalyptic atmosphere, then you may find the couple to be a bit abrasive at times. You know, the typical scenarios like Kiruko barging in on Maru while he's looking at stained porno mags that he found under someone else's bed. "Noooooooooo! It's not what it looks like, mommy. I'm not looking at porn. I don't even know what porn is. You didn't see this." Maru stuffs the porn under the mattress. "What porn are you talking about? I don't see any." Luckily, the humor is sporadic and never saturates the scenes for too long. There's even a plot-relevant "sexy time" humor bit, which is a more layered spin on a cliche scene common to harem, but for every time I get immersed into the world, I get buried neck-deep into a horny coming of age scenario all of a sudden.
The humor becomes more forceful once Juichi is introduced in ep 9; he delivers (alleged) backstory in a way that's infodumpy and obtrusive, then by episode 10 we're treated to a lot of exaggerated animation to mine humor; at one point, Kiruko's face looks like a Shin-chan character, the mains likewise fall into childish caricatures in a more limited animation style, and there are slapstick head conks and all that stuff. I honestly enjoyed the animation and humor in the episode, but even though HD dabbles a good bit in humor, the exaggeration here is perhaps too much of a tonal shift. It would have worked great as a dynamic guest director episode in a pure comedy series, but considering HD fluctuates between humorous banter and a darker atmosphere, it's a bit heavy here.
Similarly, the sadder emotions are sometimes forced, such as the hamfisted scene where a character cries after another character's death and there's sappy music playing. We hadn't even followed the characters for long, and it struck me with the force of a laugh track in a bad sitcom. I know it may seem petty to single moments like this out, but they can do a lot of damage to the work, and it's obvious that this scene was stronger in the manga; the edgy twist of episode 10 is also not doing the series any favors. On the other hand, the lighter moment between Mimihime and Ohma is much more impactful, without any music.
It's probably helpful to point to the Japanese folklore lightly woven into the tapestry of the surroundings to provide context, as most Japanese watching the series will be aware of the references going in. Izanagi and Izanami are a brother-and-sister pair (which is also important in light of how the author explores brother-sister relationships) of deities who engage in an incestuous union to give birth to the deformed Hiruko, whom they abandon. Not only does Hiruko have fish-like characteristics, but he also grew extra appendages and other unnatural features. Hiruko is a name the maneaters are often referred to as, and most of the designs appear inspired by oceanic creatures. Additionally, creation myths, including that of Japanese folklore, involve heaven and earth separating.
The art and animation are solid compared to most seasonals. The polish often expected of Production IG is here, and HD is not a pan-tastic slog like so many other seasonals. There's a mixture of character acting and effects with smoothly rendered animation, but most of the budget goes into chase sequences, beat-downs of thugs, or the elaborate monstrosities that are the man-eaters. The backdrops are solid for the wasteland and help consolidate the atmosphere a bit, but the lab scenes are admittedly flat in comparison, looking like your generic lab in any other series like this, and more dramatic lighting or framing might have helped for such a monotonous and sterile setting. The choice of "alt-idol" music in the OP fits the kind of impassioned (in the lustful and non-lustful sense of the word) teenybopper post-apocalyptic tone the series has. Both the OP and ED have a lot of impressive work put into them, and the ED seems to purposively add its male and female vocal duo to reinforce the themes of the series.
I think my main problem with the show is how it appears to thrive on atmosphere, yet the assumption is somewhat illusory (or maybe I should say delusory). Weird animeisms, awkward teenage character dynamics, out of place humor, and Maru going chop socky on everyone all the time, can kind of suck the life out of the atmosphere sometimes. The environments and slower moments are sufficient enough to maintain a partial atmosphere but not to sculpt a great one.
