Motoko Aoyama's older sister Tsuruko arrives at Hinata Inn to pass down leadership of the family dojo, only to find that Motoko has not yet surpassed her in swordsmanship. Tsuruko's ultimatum is blunt: beat her in a duel, or marry Keitaro Urashima instead. Motoko, who has spent her life putting the blade before everything else, is caught between her martial legacy and a marriage she never wanted.