The place where the girls gather is filled with colorful chatter. Gripes about studying for an upcoming test. Conversations about clothes and nails. Giddy gossip that quickly becomes petty quibbles.

Just another day in their lives.

"It feels like my hair gets all messed up the moment I so much as, like, breathe wrong," says a timid girl.

But a more earnest girl is quick to admonish her.

"Seriously? That's such a silly thing to worry about. Our hair is always going to get messed up in combat anyway."

Each girl in the classroom holds an imposing tool of war. They are android soldiers, machine lifeforms fighting on behalf of humanity. They are known as the experimental YoRHa F Squadron.

They wear black sailor uniforms. They give off cheerful laughter. And they wield guns and blades. Their daily lives resemble those of typical schoolgirls and soldiers both.

"But fighting in frilly clothes is SO much more fun."

"I bet it'd be fun to have a cute pet from Earth!"

"But I mean, if you were to date a male android..."

As the girls chat among themselves, a kind girl feels herself being watched. She whirls around.

"Ma'am!"

It's none other than the instructor.The harsh gleam in her eyes turns the girls' delighted faces into tense frowns. After a stern reprimand of the girls' lackadaisical manners, she gets right down to business.

"I will now brief you on your mission."

It's a mission far greater in scope and far more intense than any other they have embarked on. When the briefing ends, the girls all bow in unison. And in unison, they speak. It's an adage they've spoken countless times before, and so long as this war continues, will speak countless times to come.

"Glory to mankind!"

The experimental YoRHa F Squadron is made up of android soldiers who battle machine lifeforms. They once again find themselves engaged in battle on the Earth's surface. A cluster of ruined buildings covered in leaves serves as their battlefield.

Leading the charge is a rough and wild girl whose fierce sword blows make sparks fly. She demolishes her enemies in the blink of an eye. But she drops her guard for the briefest of moments, and a machine lying in wait lunges at her. As her life flashes before her eyes, cover fire rips the assailant to shreds.

Her savior is a level-headed girl, gun in hand. The two stand back-to-back and face their enemies once more.

"Much like your exam scores, your strategy is sorely lacking."

"Is that REALLY relevant right now?"

They bicker even in the midst of battle, yet their teamwork is every bit as fiery. Their movement is one, as though they are a single organism.
However—

A massive machine comprised of many limbs leaps up from the ground. The girls are quickly overwhelmed by its extraordinary strength. They stand little chance.

"Ma'am! What should we do?"

The wild girl asks for instruction through her comms device, but her instructor does not answer.

"Crud! Don't hang up on me now!"

Hurling abuses at the device, she turns her gaze to the heavens. They have been abandoned on this blue planet, left to wither beneath its vast sky.

Meanwhile, in a room of a ruined building not far from the battleground — The instructor speaks to someone on her own comms device, but it is not the girls who requested help.

"Affirmative. They engaged the target right on schedule. If all goes according to plan, they will be defeated within twelve hours."

Her cold voice reverberates through the dim room before vanishing.

The experimental YoRHa F Squadron.
Android soldiers who take the form of young girls and battle machine lifeforms on the surface of Earth. But they now find themselves cornered, met with a massive and powerful adversary.

The earnest girl lies still in a puddle of red liquid.
The timid girl wails and rushes to her side.
Her squadmate's death leaves her reeling, unguarded.
The enemy takes advantage of the opening to lay waste to her.

"Sis..."

The timid girl utters, crumpling atop the earnest girl. They were twins, created together. Together they were born, so together they should die—it's what the timid girl always wanted. And so she lay atop her sister's corpse, waiting for her functions to cease.

In the blink of an eye, the entire squadron is eliminated. The sounds of clashing swords and flying bullets cease. The only sounds that remain are those of nature. Grass rustling in the wind. Birdsong. The planet after humanity's departure is full of life.

And amidst it all, the androids lie, reduced to lifeless mechanical dolls. Never managing to become one with the planet, they now lie broken and scattered.

Hours pass.

The girls' instructor arrives on the battlefield.
She pulls out the corpses with ease, and when she grabs the arm of a particularly well-dressed girl—

"Ngh..."

She gives a faint groan. She is the most skilled fighter of the squadron—her unpredictability always made her stand out from the rest.

The instructor tenses. Would the girl cut her down?
After all, she ignored her calls for aid.
However...

"I'm so glad...you're safe...Ma'am..."

Her final words. Her functions cease.

The instructor stares at the girl's silent corpse, and then murmurs...

"Fifteen hours, six minutes... You lasted longer than I expected."

The girls — the android soldiers—faced an impossible battle against the machine lifeforms.

A battle that ended in their demise.
But this is hardly their end.

"Are you awake?"

"Yes, Ma'am!"

The kind girl sits up in her bed and gives an enthusiastic reply.
She has no memory of dying on that brutal battlefield.
She is a mechanical soldier — her death means little. Her body can be repaired, and put back into working order. Her memory, however, only exists up to her last conscious backup. There, she has no memory of her own death.

Her pain, her despair, her overwhelming love — vivid memories at the very end of her life, forever forgotten. And so the experiment continues as the girls are thrown into battle after battle.

That is the purpose of the experimental YoRHa F Squadron. But the girls do not know this. Only the instructor is aware of their true nature. Once the instructor ensures they have all awoken, she whirls on her heel and returns to her office.

And at that moment...
She senses an anomaly within her.

Ma'am. Ma'am. Ma'am. Ma'am. Ma'am. Ma'am...

The girls' voices have seared themselves into her memory, swirling round and round in her mind. They are rowdy. Eccentric. Selfish. Soldiers who are much too difficult to manage. They are cheerful. Kind. Innocent. Soldiers who should never step foot on a battlefield.

The instructor is distressed.

Under the orders of those above her, she deceives the girls. And all she can is watch them die, over and over again.

Glory to mankind.

She has long stopped believing in those words. What is it they even fight to protect? What is her purpose as their instructor?
The sound of footsteps draws her out of her daze.

"Are you all right, Ma'am?"
It is the voice of a quiet girl. Though she was not part of the previous operation, she is the android soldiers' — humanity's — trump card.
"I'm fine," the instructor curtly says.

As her gaze pierces the girl, she comes to a conclusion.
It is her duty to lead and protect the girls as their instructor. Her title is also her curse, and it will cause her continued pain. But come the next battle, she will set out with them all the same. One day, this never-ending cycle of death and rebirth will become one of hope. She holds fast to this belief.