About half of the second season of Knights of Sidonia is in the vein of the best of what the show had to offer in its first season: a bone-rattling space adventure with high stakes and grand visions. The other half feels like it was spliced in from another show that might well have been named Clone Girlfriend Tentacle Diary. It's so jarring, so tonally unlike the rest of the material around it, that it feels like a bad compromise. I haven't read the original manga (yet) and so I can't say if this was a part of the original story, but if it was, that's further evidence towards the idea that looser adaptations aren't always a bad thing. The good things, though, remain pretty good, in line with the original season being a safe way to bring an anime-watching audience to Netflix.
The story so far: Sidonia, a massive ark-ship plowing through space to resettle humanity on a distant planet, faces attacks by the monstrous Gauna. Ace pilot Tanikaze, an outsider who has manifested remarkable skills with the Gardes — the giant fighting machines used to keep the Gauna at bay — has found something like a home amongst his fellow pilots. Newest among them is a synthetic creation forged from Sidonia's labs: Tsumugi Shiraui, a sort of sentient ship with a chirpy, effervescent personality.
Tsumugi's powers resemble the Gauna's, but "she" fights for Sidonia and humanity — and "she" also forms a puppy-dog-affection relationship with Tanikaze. Since Tsumugi is enormous, and immobile when dry-docked, Tanikaze rents an apartment with ductwork "she" can work a friendly tentacle into. This makes things awkward, ho ho, for both him and two of the other people in his life. One is Izana, the non-gendered pilot whose attraction to Tanikaze makes her tilt female (an idea that's executed less artfully than it ought to be); the other is Yuhata, whose fondness for Garde models winds up being the most distinguishing thing about her.
More interesting are the ones who scheme behind the scenes to steer the course of Sidonia, both literally and metaphorically. Their storyline is given just enough screen time to move things forward, but not enough to be deepened in any real way, and in the end it just gets short shrift in favor of both the battle sequences and the cutesy byplay between Tanikaze and his friends.
Much of the split between what works and what just seems passable, I chalk up to Tsutomu Nihei, author of the original manga. Nihei's strengths have always been visuals and concepts (Blame!, Biomega), with stories and characters as an afterthought. Like Masamune Shirow, I always longed for him to hook up with a writer who could give his sensational images something to do other than just look great. Sidonia is more character-oriented than his previous work — at least, the TV series is — but the best parts of the show remain the spectacular spatial and aerial combat sequences. CGI provides tremendous uninhibited freedom of movement when used properly, and it's used more properly than not here to throw us headlong into the action with gut-wrenching results.
I also found myself liking how Sidonia explores its own environments. SF is at least as much about commenting on the present as it is considering the future, and while I'm not sure Nihei was doing this consciously, the spaces depicted in the show seem like allegories for or allusions to Japan's own physical state. Whenever the colony makes a course correction, it's racked by gravity-quakes (read: earthquakes); its national treasures and heritages contrast sharply with the acres of faceless cement elsewhere; and its dwellings are a mix of old and new — in this case, the new being a tangle of Brazil-like ductwork instead of the overhead powerlines that entangle many a neighborhood.
I always feel guilty about letting my attention and curiosity wander into the corners like this. The show itself isn't a bad one, and most of its intended audience will be only too happy to look past the flaws I cite in it. But those flaws don't come without consequence, and one of them is to produce a show that feels too much like it's second-guessing the need to be funny or cute to be effective. My theory about why Sidonia ended up on Netflix was not to bring Netflix audiences to anime, but rather to give anime watchers that much more of a reason to stick with Netflix. The second season, even for all it has going for it, only strengthens that view.