Children Who Chase Lost Voices

Eleven-year-old Asuna lives with a nurse mother who works long shifts, leaving her to fill the house with solitude and the mysterious music from the cat's-whisker receiver her father left. She spends her days in quiet isolation, rarely far from her loyal cat Mimi. The calm is fragile, hinting at the strange world that will soon intrude.

On the way to her clubhouse across a bridge, Asuna is attacked by a terrifying creature but is saved by a mysterious teenage boy named Shun. They share a moment over a radio broadcast, and Shun explains he has come from a place called Agartha in search of something. He plants a blessing on Asuna with a kiss on the forehead and promises to return the next day.

Shortly after their encounter, Shun gazes up at the sky and falls to his death, leaving Asuna shaken and alone. The bridge becomes a place of memory as the mystery of Agartha begins to unfold. The moment tests Asuna’s resolve and loneliness.

The following day, Asuna's mother mentions a boy seen in the river, while at school Mr. Morisaki lectures about Agartha and the old keeper of the dead, the Quetzalcoatl. Intrigued, Asuna visits a hidden hideout and meets a second boy who resembles Shun. Suddenly, armed men—the Arch Angels—launch an assault, forcing the boy and Asuna to flee into an underground cavern.

In the cavern, the mysterious boy refuses to kill the Quetzalcoatl gatekeeper and entrusts Asuna with a crystal known as a clavis. The Arch Angel commander captures Asuna and uses the clavis to open a gateway to Agartha. The boy, revealed as Shin (Shun's younger brother), fights back as their identities unfold.

Morisaki leads Asuna into Agartha through an underwater entrance, with Mimi in tow. They begin a journey toward the Gate of Life and Death, heading toward Amaurot where Shin learns that Asuna carries a fragment of the clavis. The path is fraught with danger as the two worlds collide.

Asuna is kidnapped by the Izoku, a shadow-dwelling race, and meets a young girl named Manna. Shin helps them escape, but he is wounded in the process, forcing the trio to continue their perilous journey with a healer's caution.

The group arrives at Manna's village, where villagers are wary of top-dwellers but offer shelter for a night. Mimi remains with the villagers, while Shin, Asuna, and Morisaki press on the next day toward Amaurot by boat. The following morning, Shin learns Mimi has died and the villagers offer her to the Quetzalcoatl in a ritual.

Asuna and Morisaki depart by boat while Mimi stays with the villagers; Shin wakes to find Mimi dead, and the villagers prepare to attack. Shin fights to protect Asuna, while Morisaki trades a gun for a clavis shard with Asuna, who refuses to descend the cliff.

Asuna lingers by the river, reflecting on Agartha and her loneliness as the Izoku return and the water dries up. Shin saves her again and they witness the Ark of Life descend. A Quetzalcoatl sings a final song, and Asuna realizes the last song she heard belonged to Shun.

The gate to Life and Death opens, and Morisaki has already wished for Lisa to come back. Lisa's soul seeks a vessel and possesses Asuna, prompting Morisaki to pursue a desperate plan. Shin sacrifices the clavis to free Asuna, and Lisa departs her body, leaving Morisaki devastated.

With the burden resolved, Asuna says farewell to Shin and Morisaki and returns to the surface world. She carries the memory of what she has learned and the people she has grown to love, promising to carry on.

A year later, an older Asuna stands at her window overlooking the cliff where she first met Shun, and she goes back to finish her schooling at graduation. The image closes on a hopeful note that she has found a new balance.