On rainy days, Hina Katagiri dreams of playing as a child with a mysterious boy in a garden she has never seen. Then she stumbles into that very place and meets Takaaki Hongou, a young man who takes her for his fiancée, Hinako Kitamine. He brings her to what he thinks is her home, where her double is waiting, and Hina learns she has landed in Japan in 1907. Having also lost her great-grandmother's heirloom necklace at the Hongou house, she keeps posing as Hinako with the real girl's help. The plan grows shaky as Hina begins to fall for Takaaki and her way back home becomes less certain. The result is a romance with comedy, drama and a supernatural twist.