Wataru Mitani is a quiet and unassuming fifth grader living in Japan. His world takes an unexpected turn with the arrival of a new student named Mitsuru Ashikawa, who begins attending Wataru's school, albeit in a different class. Amidst the excitement, unsettling rumors start to circulate about the ominous Daimatsu building, an abandoned and unfinished structure located near the school. Witnesses claim to have seen mysterious ghostly figures wandering behind the building's blue tarps, stirring up curiosity and fear among the students.
One fateful day after school, while Wataru is out with his uncle, he sees an elderly man entering the derelict structure. Driven by curiosity, Wataru decides to follow him. This decision thrusts him into the extraordinary world of Vision. There, he learns about the Porta Nectere, a mystical portal that opens only once every ten years for a brief period of ninety days. Visitors from Wataru’s world can only enter Vision if they earn the title of Traveler from "the gatekeeper," although the poignant news is given to him that all memories of his visit will eventually fade away.
Upon re-entering the Porta Nectere, Wataru is jolted back to reality as his uncle awakens him, revealing that his adventure might have been nothing more than a dream—one stemming from a fall he took down the stairs of the Daimatsu building. However, his homecoming brings even greater turmoil: Wataru discovers that his parents are divorcing, and his father is leaving with his mistress, leaving both Wataru and his mother devastated. This distress serves to compound Wataru's anxiety, as he realizes his memories of Vision are dissipating.
As tensions escalate at home, Wataru's father's lover confronts his mother about their fractured relationship, further complicating Wataru's emotional landscape. In a moment of desperation, Wataru's mother attempts to take her own life by leaving the gas on in their home. Thankfully, Mitsuru visits Wataru in this critical moment, alerts him about the gas, and encourages him to return to Vision if he hopes to alter his destiny.
Determined yet troubled, Wataru fights to recall his previous experiences in Vision. Eventually, he returns to the Daimatsu building once again, ready to cross through the portal and embark on his journey within Vision.
Upon his arrival, he encounters an old man who introduces himself as the Wayfinder. This figure reveals the path Wataru must take to change his fortune: he is tasked with collecting five gemstones to gain access to the Tower of Destiny, where the Goddess grants one wish to each Traveler. Each gem possesses unique traits—representing charity, bravery, faith, grace, as well as the duality of light and darkness. Throughout his adventures, Wataru meets both allies and adversaries, gradually coming to grips with his own inner conflicts and the nature of his being.
While the central plot remains similar to that of the original novel and manga, certain elements are reimagined. For instance, Kaori Matsushima emerges as a secondary character with limited relevance in the novel, yet in the manga, she takes on a more significant role as another License-holder. Her connection to the Matsushima Shrine, which owns the Daimatsu building, also comes to light, revealing a deeper narrative intertwined with her family’s financial dilemmas.
