在千葉道场，有一位叫裕子的少女，她和恋人健児一起来这里练习武术。道场主千葉对所有弟子都严格但又温暖地指导，而对于裕子这个孤苦伶仃的少女，他尤其关注备至。

裕子靠在居酒屋打工来维持生计，居酒屋的主人大山夫妇早已经成了她的替代父母。在训练结束后，裕子会来到繁忙的居酒屋里，拼命地做着兼职工作。而就在这时，一位名叫弘美的女性穿着迷人的迷你裙走进了居酒屋。她声称自己是裕子19年前失散的姐姐。裕子难以置信，但又信任着弘美，毕竟弘美谈起只有家人知道的秘密。

随着时间的推移，裕子和弘美共同生活在一起，她们的姐妹情深。弘美也成为了裕子在道场和居酒屋工作之外的支持者。在姐姐的陪伴下，裕子变得更加坚韧，她的剑术也不断进步。

然而，随着姐妹之间的感情日益加深，弘美似乎隐藏着一些不为人知的秘密。裕子开始怀疑她姐姐的真实身份，同时也对过去发生的事情产生了疑问。她决定去探寻真相，不仅是为了自己，也是为了弘美。

In Chiba Dojo, there is a girl named Yuko, who comes here to practice martial arts with her lover Kenji. Chiba, the master of the dojo, guides all his disciples strictly but warmly, and he pays special attention to Yuko, a lonely girl.

Yuko makes ends meet by working part-time at an izakaya. The owners of the izakaya, Mr. and Mrs. Oyama, have already become her surrogate parents. After training, Yuko would come to a busy izakaya, working desperately at a part-time job. And just then, a woman named Hiromi walked into the izakaya wearing a charming miniskirt. She claims to be Yuko's lost sister 19 years ago. Yuko couldn't believe it, but trusted Hiromi, after all, Hiromi talked about a secret that only his family knew.

As time goes by, Yuko and Hiromi live together, and they are sisters. Hiromi also became a supporter of Yuko outside of her work at the dojo and izakaya. Accompanied by her sister, Yuko has become more resilient and her swordsmanship has continued to improve.

However, as the relationship between the sisters deepens day by day, Hiromi seems to be hiding some unknown secrets. Yuko begins to doubt her sister's real identity, as well as questions about events in the past. She decided to find out the truth, not only for herself, but also for Hongmei.