After the defeat of the Guana in the previous battle, Sidonia has decided to go on the offensive and take the titular “Planet Nine” from a Guana as a strategic base for future operations. With the aid of a new ally in Tsumugi, a Guana hybrid created by Kunato, the battle finally looks to be going in Sidonia’s favor. But can Kunato be trusted given this previous actions?

Please note that there may be spoilers for Season 1 below. A review for Season 1 can be found HERE.

Rival 2.0

Whereas the first season set Kunato up as a jealous rival that meandered toward the end, season 2 instead gives the character a new lease of life. For better or worse, Kunato is now completely different from before. However, doing so allows for a much stronger and intelligent character that actually has the motivation to try several plans to further his goals rather than giving up after realising the consequences of the previous endeavour.


Kunato now has a clear goal that puts him at odds with Tanikaze and actually helps create a more interesting conflict between the two rather than merely being a matter of who was able to pilot the Tsugumori. It is unfortunate that the transition into what he becomes this season was done out of a necessity to keep the character relevant to the story rather than something that could have happened naturally, but it is still enjoyable.

Better Fight Scenes

Whilst the action scenes in the first season were some of its standout pieces, the second season has gone above and beyond. The action scenes now feel even more fluid and kinetic than before and every blow feels like it has more of an impact. Softening up on the more hard sci-fi elements has also allowed for more leeway in the fight scenes as they are now far more over the top, with Tanikaze surviving situations he would have had no chance of making it through before. However, this does not detract from or ruin the immersive experience as these scenes are very easy to get caught up in and they quickly impress with good choreography.


More time in this season is spent showing the female cast out of their uniforms and either naked or as close to naked as is possible when it is not necessary to do so. For example, Tanikaze accidentally encounters two of the clone sisters in a state of undress and they knock him unconscious as a result (the whole thing including nearly killing Tanikaze is played for comedy as well, which I disliked). This is something that I expect more from light novels and not from a hard sci-fi series. Although fan service can be used to good effect, here it is just distracting. And, more importantly, scenes such as the one above just do not coalesce well with the atmosphere the series is trying to keep and could have been cut to save time and/or adapt another potentially more important scene.

The face that launched a thousand ships

The unwanted harem is a typical anime trope, but one that I don’t think was either needed or wanted in KoS. We already had a love triangle between Tanikaze and two of the remaining cast, which covered a lot of time but also alleviated some of the darker elements of the series by adding some comedy.


Unfortunately for the second season, it has become almost a prerequisite for any female character to become a potential love interest. This does a disservice to a large majority of the cast. In particular, Sasaki, who showed no romantic interest in Tanikaze in season 1, is now asking him to “Photosynthesise” with her.

In addition to that, aside from one new character (more on that below), only Izana and Yuhata actually have any semblance of a chance of being in a relationship with Tanikaze, so developing characters this way just seems pointless. Tsumugi (the new character) is given much more development (and meaningful development) as a romantic interest and is seemingly the main love interest. As such, I would have prefered more character growth for Izana and Yuhata outside of being Love Interest B and C.


This character basically comes in two forms to me. When we see her as a Guana/Mech, she is quite a powerhouse character and has fun with the other pilots. At these times, she is rather confident with a berserker streak, making her an interesting character in the fight scenes. However, then we get to her more “meek” appearance as the “Tentacle”... and any immersion that I have in a scene is broken purely because the tentacle completely flies in the face of the hard sci-fi setting established. The concept is too ridiculous to fit into its own premise. It is unfortunate since this could have been completely side-stepped had she just retained her prior “humanoid” appearance as was already established. She would have fit into the world much better this way compared to the design the writers chose.

On the other hand, I do like the character. Her interactions with the rest of the cast are fun and Tsugumi gets the most character development this season, which is very important as she is the only character in her unique position, so hearing more about her is always interesting.

I would like to have had more insight into the implications of her existence for Sidonia, such as how others may feel they should treat her either as a potential enemy or as a saviour. This would have helped us see more into the world building, but after her first appearance it is dropped rather quickly.

What the Hell Council?!

The council members are absolutely useless contributing nothing to the overall story in the first and second seasons. They talk about the events around them and how to take action against Kobayashi for her schemes but then nothing comes about as part of these discussions. They are hyped up to be a powerful entity but it goes nowhere. For the importance placed on the council in-universe, not only is this a poor choice, but it means that any expected pay-off the audience was hoping for is completely wasted when this goes unfulfilled for yet another season.

Throughout this review, I have made many references to the previous entry in the series. However, I feel that this is because the season itself invites the comparisons. For a series that started by trying to differentiate itself from the rest by playing with and averting so many tropes, The Battle of Planet Nine instead feels more like a “paint by numbers” follow up that never reaches the highs of the previous season and adds some more cliches such as harems for good measure. This makes this series feel more run of the mill than a true follow up to season 1 should be. I would say that season 2 is watchable and I personally enjoyed parts of it, but you can only really do so if you’re willing to accept that this season will not have the same tone as was previously established.

Knights of Sidonia is currently available for streaming on Netflix.