Ever since graduating from college, 23-year-old Meiko Inoue has held one belief: a demon lurks in Tokyo. This evil's presence has left her bored, aimless, and longing for the excitement of her youth, prompting her to ponder what she truly desires from life. Surprisingly, when Meiko suggests quitting her job to her boyfriend, Naruo Taneda, he agrees in a groggy manner. Deeply inspired by his half-asleep words of encouragement, Meiko hastily abandons her old life to start anew, with Taneda soon following suit. Together, they revisit their college-day dreams and decide to revive Rotti, Taneda's former band. As the pair stands confidently beside their old friends, instruments in hand, life delivers an unexpected curveball, leaving Meiko and her friends to piece together what has been shattered. Solanin tells an intimate story about the trials and tribulations of love, loss, and grief, centered on people in their twenties who often slip through society's cracks.