In a world where strange creatures, ancient technology, and supernatural powers exist alongside ordinary cities, there is one place that doesn't appear on any map: Aokiri City. The city is surrounded by a mysterious barrier called The Veil. Nobody knows who created it—or what lies beyond it. Every few years, people inside the city begin to disappear, and those who return are never quite the same. Kyōyama Kazusa is a quiet girl who lives near the edge of Aokiri City. She seems like an ordinary student at first, but Kazusa has a secret: she can hear voices coming from beyond The Veil. Then you (boy/girl) accidentally time travel to that year.