|Title||Tanikaze Nagate's Choice|
|Rōmaji||Tanikaze Nagate no Sentaku|
|Chapters and Volumes|
With a single broken rule, Tanikaze Nagate's whole world changes and a choice is given.
After Tanikaze's Grandfather passes, he is forced to break his Grandfather's rule and goes to steal rice. While there however he is discovered and apprehended.
Tanikaze is detained and questioned as Sidonia's family records show his Grandfather having passed 17 year earlier and show no one with his name. While being questioned, Tanikaze passes out from lack of food and wakes up later in medical care.
There, he meets Ochiai who is acting as a representative for a mysterious benefactor who wishes to act as guarantor for Tanizake's identity.
After he is discharged, he goes with Ochiai to be introduced to his guarantor.
Later, Tanizake is set up in the dormitories, where he once again runs into Shizuka Hoshijrio, who was there when he was first detained. She attempts to help him, but he is still caught without a safety belt and is forced to do a check of all the anchors. Along the way stumbling into the women's photosynthesis room.
The next day, it is shown that he has joined the Academy and is forced to introduce himself to the others in training. Including many of the women whom he had stumbled upon the day before.
At the Immortal council however it is revealed that a Samghata ship has been spotted nearby, but has yet to show signs of aggression. The Council is divided on how to proceed with this information. Kobayashi's vote is the deciding one.
Later, as Captain she makes the announcement that the Gauna has been spotted and that they are once again at risk from the Gauna attacks. It is also revealed that she is Tanikaze's mysterious guarantor and gave him the chance to become a Guardian Pilot.