The series opens three hundred years in the past, where a rivalry is taking place between the Yagyu Jubei and Ryujoji schools. Yagyu Jubei defeats the Ryujoji school champion, but is dying of his wounds. Before his death, Jubei told his companion Koinosuke to find someone with "plump, bouncy bon bons" and give her an eyepatch that contains a lifetime's worth of sword techniques. Koinosuke spends the next three hundred years looking for Jubei's successor.
The main character of the series is Jiyu Nanohana, a 14-year-old junior high student who is attending a new school at the beginning of the first series. Her father has nicknamed her Jubei, and several people at school start to call her by that name. Jiyu's voluptuous figure makes her popular with the boys right away, and she attracts the notice of Koinosuke when she ends up lost in the woods on the morning of her first day of school.
After school on the first day, she is approached by Koinosuke, who gives her the Lovely Eyepatch. By the end of the first episode, Jiyu has defeated her first opponent, and she takes on the responsibility of being Jubei's successor. Koinosuke also ends up entrusting Jiyu with his master's sword and the "Koinosuke Whistle," which is what Jiyu can use to summon him if he's needed. Koinosuke is a good-hearted person and tries his best to serve both Jubei and Jiyu.
Jubei-chan: The Ninja Girl utlizies a "cute" look in its animation, but it's not a series being aimed at a younger audience, especially with all the emphasis put on Jiyu's figure in the first episode. Personally, I would recommend Jubei-chan: The Ninja Girl to anime viewers who are 14 or 15 years of age and older.
| The Secret of the Lovely Eyepatch | 13 | 1999 | Akitaro Daichi | Madhouse | Media Blasters |
| The Counterattack of Siberia Yagyu | 13 | 2004 | Akitaro Daichi | Madhouse | Media Blasters |
