Whenever it rains, high school student Hina Katagiri dreams of her younger self playing with a boy in an unfamiliar garden. She dismisses these visions as childhood fantasy until she finds herself magically transported to that very location, the backyard of a mansion. There she meets Takaaki Hongo, who mistakes her for his fiancée, Hinako Kitamine. Believing she is still dreaming, Hina plays along until she comes face-to-face with the real Hinako, her exact double, and realizes she has been sent back to Japan in the year 1907, the Meiji era.

Trapped in the past and having lost her great-grandmother's heirloom necklace on the mansion grounds, Hina accepts Hinako's assistance to masquerade as her in order to access the Hongo household and search for her way home. As Hina navigates the complex social dynamics of a Meiji-era noble family, her plan becomes complicated by her growing feelings for the melancholic Takaaki. The path back to her former life grows increasingly uncertain as she becomes entangled in a web of family intrigue and a romance that transcends time. The series follows Hina's struggle to return to the twenty-first century while caught between her identity and her doppelganger's life, exploring how her mysterious childhood connection to Takaaki may hold the key to her journey.