Wataru Mitani is an average fifth-grade student in east Tokyo. Rumors of ghosts in a deserted, semi-built edifice lead this young boy and his friend Katchan to investigate it on their own. The next school day, they learn of a new transfer student named Mitsuru, a mysterious, handsome young boy whose standoffishness and manner of speaking make others think he’s far older than a middle-schooler. He becomes a centerpiece of the ghost rumors when he seems to accidentally take a picture of one while on an art class outing near the building. Meanwhile, Wataru starts hearing a mysterious voice at his home. He convinces himself that it’s a fairy à la his favorite video game, pushing him to follow Mitsuru’s lead and take pictures around his room in the hopes of catching a glimpse of the voice’s owner.  

Trouble begins for Wataru during a visit from his paternal Uncle Lou when the two decide to investigate the abandoned building. After his uncle steps away to take a call, Wataru sees a golden door appear within the building, out from which steps Mitsuru. Both boys are shocked. Mitsuru immediately returns through the door, and Wataru attempts to follow him. Through the door, Wataru finds himself falling a great distance. He lands in a desert and shortly thereafter becomes surrounded by strange wolves with large, corkscrew mouths. He is saved by a wandering humanoid bird who reveals that he is known as a karulahkin and that the world they are in is known as Vision.  

Our protagonist then awakens in the home of the building’s owner with his Uncle Lou at hand. When Lou attempts to take Wataru back to his hotel for the night, the boy forces out the truth: his father had called when they were in the building to inform Lou that he has decided to leave the household, divorce Wataru’s mother, and start a new life with an old lover. The entire family is devastated. Soon thereafter, Mitsuru goes missing, and Wataru overhears his mother gossiping about the murder-suicide of Mitsuru’s family by his father. That night, Wataru is awoken by the appearance of Mitsuru, dressed as a sorcerer, who explains that he has been chosen as a Traveler to journey through Vision in the hopes of meeting the Goddess of Destiny and changing his fate. He gives Wataru a pendant that should allow him to do the same once he travels through the gate in the abandoned building. Mitsuru then disappears, leaving Wataru to begin his adventure to Vision.

Once back in Vision, Wataru again meets the wizard, and he explains that Wataru must collect five gemstones and place them in hilt of this sword to gain access to the Tower of Destiny and meet the Goddess. On the way to the nearest town, he meets the lizardman Kee Keema who transports Wataru to the city, explaining the political situation of Vision along the way. The world is divided between those who believe in the Goddess and those who believe in the Old God, a deity purported to surpass the Goddess in every way. Followers of the latter are mainly ankha, what is known in the real world as  human, and they espouse great intolerance to the world’s humanoid, animal inhabitants, known as beastkin. Kee Keema agrees to accompany Wataru on his journey. Over the course of the next few days, Wataru’s main party and alliances are established: Kee Keema and another beastkin named Meena will accompany him across Vision. As they get into various mishaps, the group encounters Mitsuru, now a powerful sorcerer with no concern for the death and destruction his magic causes. The boys come to learn that Vision is a reflection of their own imagination and understanding of life. It is further revealed that the appearance of two Travelers is an omen of a thousand-year sacrifice demanded by the Goddess: two people, one a citizen of Vision and the other a Traveler, are chosen to give their lives and act as the Barrier of Light to protect Vision and the real world.

A competition arises between the two boys from Japan, each thinking that the sacrifice will be the one who completes the journey last. Wataru is always one step behind Mitsuru in his collection of the gemstones, culminating in a final clash where Mitsuru destroys the entirety of an imperial capital, virtually eradicates all citizens, and unleashes a demon horde that had only been kept at bay by the final gemstone. Escaping the carnage, Wataru manages to gather four gemstones and is transported to the Tower of Destiny, the final trial from which only Wataru emerges alive. At the apex of the tower, he finally meets the Goddess. His wish is spent, not on himself, but on the salvation of Vision from the demon hordes. Returning to the real world, Wataru uses his knowledge and growth from Vision to handle the fallout of his home situation, supporting his mother as they transition into their new lives.