A heroic character death, Hange chooses to stay behind and let her comrades push forward. Why did Hange sacrifice herself?
Hange chooses to sacrifice herself so the group can conserve their Titan Powers. The others’ powers are needed to defeat Eren, so sacrificing herself makes sense for the greater good of their mission.
She also states it’s “time to face the music” for pressing on at the cost of many lives and leading the group to this point.
Hange chooses to sacrifice herself
In Attack on Titan, Chapter 131, the remaining members of the Survey Corps are weighing their options to stop the Rumbling.
Their current plan is to use a “flying boat” (an airplane) to fly over Eren’s location in the Rumbling. They plan to drop explosions on his nape and hopefully cause a bit of damage.
As a crew works diligently to prepare the plane, Floch, who is thought to be dead, climbs into the hangar. He fires a few bullets into the plane’s fuel tank before being defeated by Mikasa.
The crew members state it could take a full hour before the holes are repaired. However, the Rumbling has already reached their location and will trample them in mere minutes.
The group of Survey Corps members stand outside the hanger, staring in fear at the oncoming Colossal Titans. Mikasa asks Armin if he has a plan, to which he replies only one.
Armin suggests using his Titan Power to slow down the front row of the Rumbling. That way, the crew will have more time to repair the ship and get it into the air.
Reiner jumps in, stating that Armin’s transformation is their best chance of destroying Eren’s nape. He suggests sacrificing himself instead, but Hange says the group can’t afford to lose any more Titan Powers.
Hange says she’s the one who led the group here. She pressed on, even at the cost of so many lives, and now she says it’s time to face the music.
Before sacrificing herself, Hange promotes Armin to the Fifteenth Commander of the Survey Corps. She considers the qualification for Commander to be an unyielding desire for broader understanding, which Armin exemplifies greatly.
So that’s the answer. Hange chooses to sacrifice herself so the group can conserve their Titan Powers.