Yoshino's grandmother passed down a peculiar piece of advice: at the 50th side road beneath the great gate, following a butterfly will lead to a fated encounter. On a summer day at seventeen, Yoshino chases one just far enough—and slips through the gate into Yoshiwara, the Taisho-era red-light district, where cherry trees are in full bloom. Two men greet her: young writer Harufumi, and the entertainer Kochou. The path home is not obvious, and the nights in Yoshiwara have a way of pulling you further in.