Mio Miyamasu, a 17-year-old high school student, grapples with the turmoil of unspoken affection for her childhood friend Arata Kishimo. A heated confrontation with him drives her to chase reconciliation during a downpour, triggering a traffic accident that hurls her consciousness into the World Border—an ethereal realm where fading memories threaten her existence. To escape, she must decipher the domain’s cryptic laws while evading Mogari, a rigid enforcer of its order.

Guided by Gimon, a plush companion, and Kiku-chan, a cryptic girl who unveils Mio’s astral tether to the realm, she ventures to a spectral lost-and-found counter and petitions a serene goddess for aid. Each step toward reclaiming her memories and securing a train ticket home forces her to confront a lifelong habit of self-sabotage, born from fear of rejection and fragile self-worth. This pattern echoes in her stifled confessions to Arata and her choice to mute her emotions to safeguard friendships, struggles that now jeopardize her survival.

A breakthrough emerges as Mio glimpses the depth of her bond with Arata, whose latent supernatural heritage—including astral projection—subtly aids her quest. Yet her fate hinges on overcoming hesitation, transforming passive resignation into decisive resolve. Through fractured memories and Mogari’s obstructions, she battles to reclaim her identity, balancing apathetic detachment with raw vulnerability, especially under academic or social strain.

Her appearance—shoulder-length brown hair, brown eyes, a ribbon-tied school uniform—mirrors her ordinary life, contrasting the extraordinary trials she faces. The narrative anchors solely on her metamorphosis: a journey from self-doubt to tenacious self-advocacy, culminating in a reckoning with buried feelings and the fractured friendship that anchors her will to return.