Set in 1955 in Kokuga, Hofu City of Yamaguchi Prefecture, the story unfolds in a town that once served as the ancient capital of Suo no Kuni. Traces of the Heian Period (794‑1185) persist today through ruins and historical place names. The protagonist, Shinko, is a third‑grade elementary student from a long‑established local family. She is known for the distinctive curl on her forehead, which she affectionately calls her “Mai Mai,” and she loves to play in the surrounding fields. Yet her secret delight lies in daydreaming about a world a thousand years in the past; her fantasies take her deep into the era of the Heian Period.