Miki begins as a high school student whose ordinary commute spirals into chaos following an argument with her friend Sayaka, catapulting them both into the parallel World of the Clouds. Disoriented and vulnerable in this strange dimension blending historical figures, advanced technology, and supernatural forces, she is separated from Sayaka when antagonists target Sayaka, mistakenly believing her possession of a bell artifact marks her as the priestess of Zeguy.

Forced to navigate this perilous world, Miki allies with warrior Toshizo Hijikata and inventor Gennai Hiraga, focusing on rescuing Sayaka and stopping the villainess Himiko from wielding the Mask of Zeguy's power. Initially dependent on her allies, she gradually asserts her own agency, confronting threats head-on to save her friend, driven partly by guilt over their unresolved argument.

A critical revelation identifies Miki herself as the true priestess of Zeguy, her heritage signified by an innate connection to the Crown of Shamas. This makes her a target for villain Komei Shokatsuryo, who uses hypnosis to try and extract the crown's location. Cornered by enemies, her latent powers erupt under extreme stress, unleashing a massive energy blast.

Her journey culminates at the World Gates confronting Himiko. Witnessing Sayaka facing sacrifice, Miki fully embraces her priestess role. Zeguy's power resonates with her protective resolve, enabling her to channel its energy and obliterate Himiko, resolving the conflict and restoring dimensional balance.

After these events, Miki returns to her original world with Sayaka, reconciling their friendship. The conclusion hints at lingering ties to the World of the Clouds, as figures like Hijikata and Gennai appear integrated into her everyday surroundings.