3-4 Main Story: Birdcages (Library Summaries)

1
The world of memories was on the verge of collapse as The Cage was relentlessly invaded by enemies. The world in which the soldier lived also seemed to be affected by this. The soldier wanders through a battlefield littered with corpses, searching for one of his subordinates—a boy who had disappeared. The soldier believes that the boy must be alive somewhere, yet he is tormented by guilt. So many lives were lost due to his own failure. Whether it was due to the pressure of failure or the effects of this broken world, he begins to hear hallucinations.
The surrounding corpses call out to him, "Everyone is dead. Everyone is dead, and it’s your fault."
In an attempt to shake these voices off, the soldier takes off across the battlefield. Blocking his way is a phantom with exactly the same appearance as himself. The phantom asks him why he is searching, to which he replies that the boy is a precious compatriot.
The vision replies, "We can't save anyone."

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The world of memories where the boy lived was about to be swallowed by raging flames. The boy searches for his lost attendant, and a thief helps the boy in promise of a reward, proceeding forward and diving into the flames.
An aberration cloaked in a white sheet—Mama—appears from behind the flames to lead the two. The boy tries to obey the words of the aberration, but the thief notices that something’s not right. The aberration approaches the two with kind words…at that moment, a woman with prosthetic limbs appears and slashes the aberration. The aberration, which was pure white, turns black and attacks with malice. This Mama is a fake.
The two repel the aberration with the help of the woman. However, the woman's hostility was then directed at the boy. The woman had realized that the boy belonged to kingdom that murdered her sister. In order to fulfill her revenge, the woman tries to kill the boy. However, the thief deflects her sword and escapes with the boy in tow.

2
The thief and the boy wander into a room in the palace. It was once the room of the princess whom the thief had loved. In the room, phantoms of the thief and the princess engage in chatter. While listening to their conversation, the thief and the boy are swallowed by waves and washed away to the night market. The thief's world is also collapsing.

The phantoms talk in the market as well. After being swallowed by the waves several more times, they finally arrive at the beach. Waiting for them on the beach is the fortune teller who ruined his plans with the princess and took his life.
The thief and the fortune teller once again fight for their lives. After the fight, the scene changes back to the room in the palace.
There, the figure of the fortune teller remains unchanged. But instead, the thief is confused by a truth he could not have known.
The true identity of the fortune teller with he despised so deeply was in fact the princess in disguise. As if to mock the struggling thief, the waves swallow them up again.

3
The boy dreams of the woman with the prosthetic limbs. In his dream, the little sister who was supposed to be dead appeared beside the woman who swore revenge. Holding her sister in her arms, the woman's hatred grows...
The boy wakes up and runs through the palace with the thief, heading back to the princess. But when he sees her, the thief is shaken, and rendered unable to move. As the boy worries, the scene changes to that same town he saw in his dream. There, a woman tries to exact her revenge. And appearing there are none other than the sister who has become a weapon and the fortune teller. In order to help the two, who seemed to not be moving of their own will, the woman and the boys join forces.

After the battle, the woman and the boy face each other in a world of pure white.
The woman's sister is beside her, and the young girl speaks her true wish...
"Don't suffer for me anymore." The woman's hatred for the boy quickly fades, and she embraces her sister and disappears.
The thief also reconciles with the fortune teller he once hated.
The boy warmly sees the pair off.

4
The boy runs through an unfamiliar battlefield in search of his attendant.
At the end of his path, he finds the attendant he has been looking for.
He confronts a man in military garb. His eyes are eerily red, and he seems to have lost his sanity. When the young man fires his gun, the attendant shields the boy and falls.
The boy was made to realize his own powerlessness.

The voice of the boy in military garb he met in the stone tower lifts the boy from his despair. Inspired by his words, the boy opens the body of the mechanical attendant. The beliefs, aspirations, and love he gained on his journey...
The boy pours out his whole heart so that he might revive his attendant.
The two, bound by their trust in each other, reunite. They join forces with the boy in military garb and succeed in stopping the soldier.
As the boy moved to care for the unconscious young man, the voice of the white aberration, Mama, urges them on. In an attempt to save themselves from collapse, the group escapes from the battlefield.