Shion, a girl who woke up in a white room, is bewildered by the warmth of the real sun streaming through the window, the sound of curtains swaying in the breeze, and the faint scent of soil and flowers. For her, who had only known the "world through glass," everything she sees is new and somehow precious.

Shion was merely waiting to be "disposed of" in a sterile laboratory. Guest, a researcher, blew up the facility to save her after she developed emotions, abandoning everything to flee. They arrived at the Chita Peninsula in Aichi Prefecture—a small town overlooking the sea, and a small white house on a hill at its edge.

The people of the quiet town at the foot of the hill warmly welcomed Guest and the slightly otherworldly girl. An old woman who delivers freshly baked bread, a florist who teaches her about seasonal flowers, a tiny stray cat... Through casual daily conversations and human warmth, her frozen heart gradually begins to thaw.

Guest started working in this town, and Shion began teaching the local children how to read and write in a classroom converted from an empty house. Living together, the two find their place in this peaceful town.

Meanwhile, the footsteps of Kuze, a former colleague and pursuer, are drawing near.