Kaina of the Great Snow Sea was the latest televised collaboration between manga author Tsutomu Nihei and CG animation studio Polygon Pictures. This team-up had previously produced adaptations of Knights of Sidonia and Blame!, and Kaina stood out as their first anime-original work developed in part by Nihei. I wrote weekly reviews of the show, and I found it to have an entrancing setting that worked evocatively on the megalithic scales Nihei is known for. Ultimately, however, the plot and characters were too flimsy to support its superstructure trees, and while I liked the series, it never awed me the way it could have. In short, Kaina was a meh story in a cool place.

I mention my impressions of the show because, by and large, they also apply to this film. As a direct continuation of the series finale, Kaina of the Great Snow Sea: Star Sage wraps up its narrative and mysteries with a reasonably satisfying conclusion, but its answers don't make up for the story's lack of urgency and creativity. While I held out some hope that the movie and its climax would capture the spark of Nihei's greater works, that flame fizzled in the waters of the Snow Sea.

The movie opens quietly with a survey of the various vistas Kaina had previously visited, and that's a smart move because the aesthetics of their dying world remain Kaina's greatest asset. The alien canopy, the Yggdrasil-esque orbital trees, the rustic human settlements, and the gnarled depths of the Snow Sea each evoke the uniqueness of this planet. The film doesn't look any better than the TV series, but the backgrounds were already gorgeous. All we needed was continuity, and we have that.

I also have a few complaints about the animation. While Polygon's style still looks stiff compared to what the CG savants at Studio Orange cook up, they've come a long way compared to their own work from a decade ago. The trench scene—probably the film's best action set piece—is a great example of their improved character acting and kinetic direction. The boat's tense vertical climb up a wall of ocean feels like a callback to the gravitational shenanigans of Knights of Sidonia, but it expresses danger and drama in a more cinematic fashion. We see the crew work together to keep the ship from falling apart, and it cements the previously shaky alliance between the Atlanders and the Valghians. While it's a basic dramatic beat, it's the movie's best-executed one. On the other hand, underwater physics still doesn't feel quite right to me, and I'm still not sure if they're supposed to be intentionally uncanny. In that regard, I applaud the mild CG jank for lending itself to the series' air of mystery.

Star Sage's true faults lie elsewhere, namely the writing. None of these characters rise above their archetypes, they have no meaningful developments, and none of their relationships have any memorable chemistry. Kaina stumbles haplessly and uncompellingly into every plot development. Ririha is sharper but boring. The new antagonist, Byozan, is your stereotypical arrogant villain. When the credits rolled, I didn't have any lingering attachment to any of their stories. These are functional characters but missing the edge and weirdness of Nihei's other sci-fi tales. While there's nothing wrong with leaning on classic archetypes, these examples feel calculated and risk-averse, and that's the polar opposite of what I want in art.

The plotting also doesn't rise to the planet-sized stakes of Kaina and Ririha's mission. I already mentioned the lack of urgency, so let me give some examples. At the beginning of the film, the tree elders give Kaina his bark cutter, noting that it's been recharged after the Builder battle. Naturally, I expected the device to play an important role later on. Instead, he drops it in the ocean about a half-hour later, and it's never relevant again, nor does anything come from that subversion.

Similarly, when it was discovered that Kaina was immune to the mind virus protecting the control room, I expected Byozan and his lackeys to leap at this opportunity. Byozan, however, hardly comments on it, and they wait until the following day to have him tackle the main corridor. It makes sense when you consider that this pause allows the Atlanders to plot their rebellion, but narrative convenience isn't an excuse for slow and sloppy plot progression. I think the writers' room had well-defined ideas for the big set pieces, but they never nailed down their connective tissue to the same degree. They emphasized the destination over the journey.

I like that we don't get an extensive definitive infodump exposition when we finally get some answers. I was dreading the possibility of Kaina reaching the control room and activating a hologram of the Star Sage, who would spend the next ten minutes detailing every part of the plan and its history. Instead, the answers given are fragmented and interpreted through the highly polarized lens of our main characters, which is a much more innovative approach. Humans have yet to figure out how to accurately preserve important information for future generations many millennia removed from ours, so this facet helps tether Kaina to reality. Additionally, the story doesn't need us to know what happened before the orbital trees were planted, and none of these characters would even understand the specifics of the science involved. I'm glad Kaina ends with some mystery intact.

That said, these revelations are neither surprising nor all that interesting. It had already been fairly obvious that the trees were terraforming the planet to repair some kind of grievous environmental damage. I like the dry humor of humanity facing extinction due to a program glitch requiring a manual override. That's a dystopian future I can believe in. But I can't quite get past the hokeyness of an administrative AI choosing Kaina and Ririha because it can detect that they, unlike Byozan, are good people. If the characters had more substance, that might have worked for me, but as-is it just smacks of more convenience for the sake of it.

I don't want to come across as too harsh on Star Sage, though, because, like the TV series, I still had a good time with it. The sound design and soundtrack work in tandem with the grand scale of the adventure. The final battle juggles each of its tiers well, with the swashbuckling laser show on the ground, the big Builder clashes above, and the slow severing of the massive trunk in the sky. And the mass exodus of the orbital spire trees, which form some kind of protective Dyson sphere around the planet, makes for a visually striking climax. I may be predispositioned to defend any one of the dwindling examples of original and unfranchised sci-fi anime we get each year. Still, I'm glad Kaina was able to finish its story. I just thought it was a strong enough story to love.