Sixteen-year-old Tsugumi is deeply in love with the handsome and popular Shougo Mizushima, though she believes he is far out of her reach. Her hopes are complicated when she learns that her mother has arranged a marriage for her to a fiancé she has never met. Refusing to give up, Tsugumi decides she must act quickly and confesses her feelings to Mizushima that very same day. However, her plans take an unexpected turn when someone else confesses to her instead: an eleven-year-old boy who somehow already knows her name.