The scene is set in Kokuga, Hofu City, Yamaguchi Prefecture in 1955, formerly known as Suo no Kuni—a once bustling capital thousands of years ago—leaving a trail of historical artifacts and names dating back to the Heian Period (794-1185). At the center of the story is Shinko, a third-grade student whose family boasts of a respected legacy within the town. She has a unique curled lock of hair on her forehead, which she affectionately calls "Mai Mai," and loves to spend her time playing in the fields. However, she also harbors a secret wish to experience life in the Heian Period a millennium ago. When Kiiko, a girl from the city, joins Shinko's class after moving from Tokyo, adapting to life in the small town proves challenging initially. But with time, their friendship blossoms and they find themselves embroiled in an unusual incident that occurred a thousand years earlier.