Aoi Aioi, a second-year high school student and aspiring bass guitarist, grew up in rural Chichibu after her parents’ fatal car accident thirteen years prior. Her older sister Akane abandoned plans to move to Tokyo with then-boyfriend Shinnosuke Kanamuro to raise her, fueling Aoi’s belief that she derailed Akane’s ambitions. This guilt propels her resolve to pursue a solo music career post-graduation, despite lacking concrete plans or collaborators.

Childhood fascination with the bassist from Shinnosuke’s band sparked her musical passion. Now wielding an Epiphone bass and VOX amplifier, she practices obsessively yet dismisses peers she deems unskilled. Her brash, tomboyish exterior cloaks insecurities about her future and fractured relationships.

A turning point arrives with Shinno—a manifestation of 18-year-old Shinnosuke’s lingering regrets. Initially mistaken for a ghost, Shinno seeks to reconcile Akane and the present-day Shinnosuke. As Aoi develops romantic feelings for him, her mission grows complicated. Confrontations with both Shinno and the jaded adult Shinnosuke unravel her assumptions about sacrifice and obligation.

Aoi’s journey pivots on realizing Akane never resented their life together, dismantling her belief that leaving Chichibu would grant Akane happiness. She also wrestles with loving Shinno, an emblem of idealized youth, alongside accepting adult Shinnosuke’s imperfections. Ultimately, she chooses to remain in Chichibu, strengthening her bond with Akane while continuing music locally.

Her arc traces self-worth and redefined dreams, shifting from isolated resentment to valuing kinship and present opportunities. The narrative explores her conflicts through dual Shinnosukes, her tense yet devoted relationship with Akane, and her evolving grasp of responsibility versus ambition.