Episode 4: Sacrifices

After killing the members of the Akai squad, the gauna proceeds en route of collision with Sidonia and Captain Kobayashi orders an emergency evasive maneuver that causes massive casualties at the ship's residential area, despite the citizens' efforts to brace themselves, but succeeds. As the gauna makes a turn back to target the ship again, Kobayashi orders dozens of guardians to defend it, and sends Kunato, Shizuka and Nagate to salvage one of the weapons used by the KIA squad to fight the gauna, the Kabizashi. However, just as Nagate's team retrieves the artifact, the gauna turns their attention to them and fires a blast that incapacitates all their units, except for Nagate's Tsugumori. Shizuka's unit goes out of control forcing her to bail out and instead of following his orders to tow the other two guardians back, Nagate grabs the Kabizashi and fights the gauna head on, destroying it with certain ease. As the others celebrate his feat, Nagate disobeys orders once more and leaves in search for Shizuka, despite being warned that he is distancing himself from Sidonia to a point of no return.