Fujiwara, an aspiring manga artist, finds his world turned upside down when his former high school teacher and unrequited first love, Yuuki, moves in next door. Yuuki, now married but often left alone due to her husband's frequent business trips, seeks solace in the friendship of her former student. Little do they know, thin walls in their shared building allow Fujiwara to overhear every intimate detail of Yuuki's life, blurring the boundaries between them in unexpected ways.