Setting: Alto, Georgia, USA

Class 1-A, their teachers, travel from Japan to the quiet mountain town of Alto, Georgia, for a week-long international exchange program sponsored by both the Japanese and American school systems. The trip is designed to promote cultural understanding through classroom activities, sightseeing, local traditions, and student-led tours.

Upon arriving at Alto High School, they're introduced to six students chosen to act as their guides: Ashlyn Banner, Aiden Clark, Ben Clark, Tyler Hernandez, Taylor Hernandez, and Logan Fields. The six are well-known around school and seem inseparable, effortlessly moving as a group and always looking out for one another. While they appear to be ordinary teenagers, Class 1-A gradually notices small oddities—Ashlyn constantly checking the time, Logan quietly observing everything around him, Tyler instinctively taking charge, Taylor always carrying supplies "just in case," Ben communicating through his phone after losing his voice years ago, and Aiden masking moments of unease with endless jokes.

The exchange begins like any normal school trip. Students attend classes together, compare life in Japan and America, eat lunch in the cafeteria, explore Alto's landmarks—including the famous School Bus Graveyard—and slowly grow closer through friendly competition, awkward cultural misunderstandings, and everyday conversations. Class 1-A experiences life in a small American town while the Alto group learns what it's like to attend the world's most famous hero academy.

Unknown to the visiting heroes, the six Alto students are hiding an impossible secret. Every night at midnight, they're dragged into the Phantom Realm—a silent, monochrome reflection of Alto where time stops in the real world and terrifying phantoms hunt anything that moves. They've survived countless nights together without telling anyone, convinced no one would ever believe them.

For now, however, none of that has happened.

This story begins in the Human Realm, where the biggest concerns are first impressions, making friends, exploring a new country, and enjoying the exchange program. Strange comments, uneasy glances, and odd habits are easy to dismiss... until the first night arrives.

When midnight finally comes, everything changes.