Hiroki Saitou (斎藤 ヒロキ Saitou Hiroki) is Nagate's "grandfather."



Saitou was the ace pilot of Sidonia for five hundred years. Together with Lala, Kobayashi, and Ochiai, he took part in numerous sorties against the Gauna. Saitou was also a founding member of the immortal ship committee. For a time, Saitou and his comrades got along, but as time passed, their friendship fragmented due to growing differences of opinions and goals in relation to Sidonia. Kobayashi had differing opinions over the future of Sidonia, while Ochiai began plotting against Sidonia in the name of survival as a species; Lala was the only who remained his faithful friend the entire time.

Ochiai's Insurrection & Going into HidingEdit

During the event 100 years ago caused by Ochiai, he and 300 others were the only survivors. The clone that Sidonia had prepared for him, died during this conflict. As Sidonia recovered gradually, Hiroki grew tired of the huge burden he had to carry throughout his career. He stopped ingesting the immortality drugs and decided to not perform a brain transplant into a younger body.

Returning to Sidonia & Taking NagateEdit

About 14 years before the story, old age had advanced on Saitou, turning him old and wrinkled. Collapsing in front of the first Organic Reactor, he was forcibly put into a coma and recovered for days under Lala's supervision. During this time, Kobayashi took his cells and forcibly made a clone without Saitou's knowledge. This clone would grow up to become Nagate.

He took Nagate, Saitou's clone, out of his incubator prematurely, viewed him as his child, and told Kobayashi that he would raise Nagate to become an ace pilot. During the fight between Saitou and the security team, he managed to make his way to the deep bowels of Sidonia, never to be seen again.

Death & LegacyEdit

Saitou died before the story started. After refusing aid from the Immortal Committee, his body aged and deteriorated. He used his final years to raise and teach everything he could to Nagate: Gardes VR training, scavenging, electrical repair, basic reading and writing skills. However, always weary of Sidonia's intentions, he made it clear to Nagate he mustn't leave their underground home. Once Nagate reached his late teens though, Saitou finally passed away in his sleep. With no supply of food left, Nagate ventured into Sidonia and began his life on the surface. Sidonia's investigators would later discover Saitous mummified body and gave him a proper burial. Although dead, Nagate would be his surviving legacy and he would prove to be invaluable to Sidonia's future and survival.

Image GalleryEdit


Knights of Sidonia Characters
Gardes Pilots

Nagate Tanikaze | Izana Shinatose | Shizuka Hoshijiro | Honoka Sisters | Mochikuni Akai | Hinata Momose | Kashiwade Aoki | Izumo Midorikawa | Eiko Yamano - Toutarou Yamano| Samari Ittan | Tonami | Kouichi Tsuruuchi | Ichirou Seii | Norio Kunato | Kaoru Hazama | Ryouhei Kasuga | Kujira Negi | Hamagata | Hashine | Suzuki

Sidonia Command

Yuhata Midorikawa | Ryouko Takahashi | Ichirou Seii | Ochiai Clone

Immortal Ship Committee

Kobayashi | Lala Hiyama | Hiroki Saitou | Yure Shinatose | Ochiai

ET Research Center

Numi Tahiro | Yure Shinatose

Toha Heavy Industries

Sasaki | Shinsuke Tanba | Shijimi

Kunato Developments

Norio Kunato - Mozuku Kunato


Teruru Ichigaya


Tsumugi Shiraui - Kanata

Gauna 487 | Gauna 491 | Gauna 492 | Gauna 493 | Benisuzume | Placental Hoshijiro | Ocarina | Gauna 541 | Large Mass Union Ship | Lem Gauna Wall | Lem VII Gauna | Aulos
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