The protagonist meets his teenage girlfriend at an essay contest ceremony and asks her to exchange letters with him.

The protagonist's girlfriend cries in a park and reveals she feels like a shadow of someone living in a walled-in town.

The protagonist receives his girlfriend's final letter saying she is fading; she never writes to him again.

The protagonist goes to college, gets a job, and attempts romance, but cannot give his whole heart to anyone.

While in his mid-forties, the protagonist falls into a hole and wakes to find the walled-in town's Gatekeeper standing over him.

The protagonist relinquishes his shadow at the gate and has his eyes altered to become the town's Dream Reader.

On his third day in the walled-in town, the protagonist discovers the library and meets a girl who looks exactly like his girlfriend.

The protagonist's shadow warns him it is dying and they must escape together through the pool by the southern gate.

At the pool's edge, the protagonist tells his shadow to jump in alone and watches it disappear beneath the surface.

The protagonist wakes in the real world unsure how he returned and quits his job feeling he needs a new direction.

After a job interview in the mountain town of Z**, the protagonist is offered the role of library director by Mr. Koyasu.

Mr. Koyasu calls the protagonist late at night and, at the library, reveals he has no shadow and died a year ago.

A teenage boy called M** sends the protagonist an envelope containing a near-perfect map of the walled-in town.

M** vanishes overnight from his home and a police investigation finds no evidence of how he left.

In the walled-in town, the protagonist blows out the candle in his consciousness and darkness falls around him.

The novel follows an unnamed protagonist whose teenage girlfriend vanishes after introducing him to a fantastical walled-in town, leaving him isolated for decades. In his mid-forties he falls into the town, surrenders his shadow, and serves as its Dream Reader beside a girl who resembles but does not remember his lost love. After his shadow escapes alone through a pool by the southern gate, the protagonist mysteriously wakes in the real world and quits his job to start over. He takes a directorship at a small private library, where his new colleague Mr. Koyasu proves to be a ghost who selected him deliberately. A teenage savant named M** delivers a perfect map of the walled-in town and then disappears overnight, while inside that same town the protagonist ultimately merges with a mysterious Yellow Submarine Boy and chooses at last to return to reality.

The central story of love lost, a fantastical journey, and a quiet return.

The protagonist and his girlfriend spend a summer mapping and recording every detail of the walled-in town she describes.

The protagonist's girlfriend's letters grow infrequent and stop entirely; when he calls her house, the number is disconnected.

The protagonist goes to college in Tokyo but makes no friends and finds another family living in his girlfriend's old house.

The protagonist asks to walk the girl from the library home; she reveals she was born inside the walls and never left.

The protagonist draws a map of the walled-in town and falls into a terrible fever; an old man comes to tend to him.

The girl from the library takes the protagonist to the southern pool, where he feels an overwhelming urge to dive in.

The girl from the library tells the protagonist she and the girlfriend he once loved outside the walls are entirely separate beings.

The protagonist dreams of working in a peaceful library where a blue beret rests on a table and decides to find such a place.

The protagonist moves to Z** and begins learning the library director role from Mr. Koyasu and fellow librarian Mrs. Soeda.

The protagonist moves his workspace to the subterranean office with the woodstove and vivid memories of the walled-in town overwhelm him.

Mrs. Soeda tells the protagonist that Mr. Koyasu's five-year-old son was killed by a truck and his wife later died by suicide.

The protagonist visits Mr. Koyasu's grave for the first time and weeps, finding him buried alongside his wife and son.

The coffee shop woman comes to the protagonist's home for dinner and he feels an unexpected change beginning in his heart.

In the walled-in town, the protagonist notices a boy in a Yellow Submarine parka watching him silently from across the river.

On the last night he walks the girl from the library home, the protagonist says farewell instead of his usual goodbye.

These events trace the quieter connective tissue of the story, beginning with the protagonist and his girlfriend obsessively mapping the walled-in town across a single summer. Their correspondence eventually breaks down and the protagonist searches for her in vain, while inside the town he explores its strange geography, suffers a strange fever, and hears the girl from the library assert that she and his lost love are entirely separate beings. Returning to the real world, the protagonist rebuilds his life step by step in the mountain town of Z**, moving into the library's underground office where smells and warmth blur the boundary between realities. Mrs. Soeda's account of Mr. Koyasu's family tragedy — his son's death and his wife's subsequent suicide — gives deep context to the ghost's lingering presence. The pool closes as the protagonist first glimpses the Yellow Submarine Boy across the river in the walled-in town, then bids a final farewell to the girl from the library.

The texture of two worlds — a summer of mapping dreams, a mountain town, and quiet goodbyes.

The protagonist's girlfriend explains that her real self was born in the walled-in town and that her present self is a banished shadow.

The protagonist's shadow argues that the girl in the library may be the shadow while the real girlfriend exists in the outside world.

The protagonist contacts former coworker Oki, who identifies a privately owned library near Fukushima as a perfect match for the job he seeks.

The protagonist notices Mr. Koyasu's watch has no hands and learns from Mrs. Soeda that she never sees him enter or leave the library.

After the loss of his son and wife, Mr. Koyasu begins wearing a skirt and blue beret and establishes the town library with brewery proceeds.

Mr. Koyasu tells the protagonist he was chosen as library director because he is a man who understands what it means to lose a shadow.

The protagonist learns from Mrs. Soeda that M**, a teenage savant who reads at extraordinary speed, has visited the library every day for years.

M** uses a notepad to tell the protagonist that the walled-in town's wall was built to prevent a never-ending epidemic of the soul.

Mr. Koyasu tells the protagonist this will be their last meeting and that M** must find his own path to the walled-in town.

The coffee shop woman confesses she has no interest in sex; the protagonist tells her he is willing to wait for her.

M**'s brothers meet with the protagonist; the younger brother proposes that the wall surrounding the town represents human consciousness.

The protagonist dreams of a wooden doll resembling M** that whispers and bites his earlobe; the pain is entirely real when he wakes.

The protagonist dreams of walking upstream and growing younger until he finds his teenage girlfriend, who says they are both someone else's shadows.

Yellow Submarine Boy appears at the protagonist's bedside in the walled-in town and explains the two of them were once a single being.

Yellow Submarine Boy reveals he knows the protagonist's shadow in the real world and tells the protagonist his heart is ready to leave the town.

This pool gathers the pivotal revelations that progressively reframe the story, beginning with the protagonist's girlfriend declaring that her present self is a banished shadow and her true self lives inside the walled-in town. Across both worlds, definitions of reality are steadily destabilized: the protagonist's own shadow challenges the identity of the girl from the library, while strange clues around Mr. Koyasu — a watch with no hands, unseen arrivals and departures — confirm his ghostly nature before he admits it. The story of Mr. Koyasu's transformation after personal tragedy, and his deliberate selection of the protagonist as his successor, reveals the deep spiritual logic connecting all the characters. The final revelations arrive through the teenage savant M** and the mysterious Yellow Submarine Boy, who between them expose the purpose of the wall, the true calling of the Dream Reader, and the startling fact that the protagonist's shadow has been living his life in the real world all along.