Sidonia no Kishi is a show with a big cast, as you might expect from a military style mecha show. Not only that; but uniforms and quick introductions can sometimes make it tough to keep track of everyone. Hopefully, I can help you by telling you a little bit about the primary cast. I’ll do my best to steer clear of spoilers here, but you should probably watch the first couple of episodes before you read further.
Nagate Tanikaze – The Outsider
Nagate Tanikaze is the protagonist of Sidonia no Kishi. He’s also our everyman character. Since he’s an outsider to the world of Sidonia (more on that in a bit), he’s a great anchor to help us understand the world as he does. When we first meet Tanikaze, we discover that he has been raised in the lower levels of Sidonia by his grandfather. He has had no social interactions outside of this, and is largely ignorant of the world of Sidonia apart from what he has been told. Tanikaze’s life with his grandfather is lived in small subterranean quarters with sparse furnishings. The only exception to this Spartan lifestyle is the Garde pilot simulator that Tanikaze trains with. We learn that Tanikaze’s grandfather has been training him since a very young age to pilot a Garde using this machine. Tanikaze’s grandfather tells him that he will need these skills to protect the people of Sidonia, a people he has never met.
Our first introduction to Tanikaze involves his excursion into Sidonia proper to steal a bag of rice. We learn through quiet exposition that Tanikaze’s grandfather has died. Tanikaze has been forbidden to go as far into Sidonia as he needs to, but hunger drives him. It is clear that his grandfather has long been a provider for the both of them, and Tanikaze has no choice but to disobey his grandfather’s wishes. Unfortunately (or perhaps fortunately), Tanikaze’s plan does not go well, and he finds himself injured and recovering in a hospital room. Tanikaze awakens in a strange place surrounded by strange people; he is scared and uncertain.
Tanikaze’s story is characterized by this very sense of exclusion. He doesn’t understand the society of Sidonia, and he doesn’t have experience with people. It’s clear that he means well, and that he wants to be accepted, but he fails socially on a regular basis. Unlike a lot of other “clueless” anime leads, Tanikaze has a good reason for his lack of social skills. Despite this, Tanikaze does his best to fit in. He is constantly apologizing and trying to make amends for his mistakes. Early on, it’s clear he hopes to use his piloting skill to help him break the ice with the other recruits. Unfortunately, he discovers that the simulator he’s become so familiar with is based on an outdated Garde model, and it appears his skills do not transfer.
Tanikaze is, at his core, a kind person who wants to help others. He has been raised with a desire to protect the people of Sidonia from well before he even met them. He works hard to become a part of the society, though he is still an outsider because of his biology and his history. Tanikaze will always agree to help others, despite the circumstances. He may be a bit naïve, but it’s his desire to help and protect others that define him and his actions.
Shizuka Hoshijiro – The Kind One
Hoshijiro is one of the first people Tanikaze meets once he finds himself in Sidonia. In fact, Hoshijiro accompanies Tanikaze when he is questioned by police after escaping the hospital. She becomes an important fallback for Tanikaze in a world where he knows very little. Hoshijiro is soft-spoken and kind. She refuses to join in when the other cadets make fun of Tanikaze. Despite her mild manners, Hoshijiro is a capable Garde pilot. In fact, she is ranked second amongst the cadets in combat simulations. Hoshijiro is not brash or overconfident, instead working to be a peacemaker amongst the other recruits. She is quite serious, despite her age, and a valuable ally.
Izana Shinatose – The Jealous One
Izana Shinatose is another recruit Garde pilot in the same group as Tanikaze. Izana is a non-binary third gender. What this means is that Izana is neither strictly male nor female, but has the ability to choose either when a suitable mate is found. This leads to some confusion initially from Tanikaze, but he does not let it hinder his friendship with Izana. Izana is one of the first people to really befriend Tanikaze. Izana is kind, accepting, and patient with Tanikaze in a way that few others are. Not only that, Izana works to help Tanikaze understand and explore the world of Sidonia. It is shown that Izana is not particularly skilled as a Garde pilot. Izana lacks confidence in this realm, and is sometimes seen to hesitate in crucial moments. Izana is certainly not the most confident of the recruits. That said, Izana is loyal, kind, and caring. Izana is a valuable friend to Tanikaze. It is also shown that Izana tends to get jealous when Tanikaze spends time alone with others.
Yuhata Midorikawa – The Investigator
Yuhata is also a recruit Garde pilot. She is the younger sister of another pilot, Izumo Midorikawa, and plays the younger sister role frequently. Yuhata is immediately interested in Tanikaze after an encounter with a large Gauna. Yuhata is forward and unabashedly curious about Tanikaze, bordering on obsessive. She has a scientific mindset and is profoundly curious about many things. She is also a capable strategist, and very intelligent.
Norio Kunato – The Rival
Kunato is the top of the class of recruits and the best pilot amongst them (at least as far as simulations go). Kunato is the heir to Kunato Developments, who are responsible for developing the Gardes that currently keep Sidonia safe. He is immediately suspicious of Tanikaze, and doesn’t like the attention that the new pilot receives.
Kobayashi – The Enigma
Kobayashi is the captain of the Sidonia and answers only to the Immortal Council. Little is known about Kobayashi, and she is generally calm, quiet, and decisive. Kobayashi vouches for Tanikaze early on. She takes guardianship of him and asks him to assist in the defense of Sidonia.
So those are the key players on Sidonia. There are many more people throughout the series, but hopefully this primer has gotten you familiar with the most important of the cast so you can keep up with the action.