Following the events of the first television series, Jiyu Nanohana was happy; her days as Jubei Yagyu the 2nd were over, and she finally felt she could live a normal life again. However, when a clan of samurai calling themselves the Siberian Yagyu want revenge on Yagyu Jubei for their banishment to Siberia 300 years ago, once again young Jiyu is forced to take up the sword as the re-incarnation of the legendary swordsman.
Six months after the Jewel Seeds incident, Nanoha is still using her magical powers to help the Time-Space Administration Bureau maintain dimensional stability. However, new adversaries involved with the dreaded "Book of Darkness" Lost Logia have appeared, wielding weapon systems that far outclass Nanoha's Raising Heart and Fate's Bardiche. Nanoha, Fate and friends must now find a way to match the strength of their new opponents and once again use their powers to prevent a large time-space disaster from happening – an event which threatens not only their world, but multiple dimensions!
Jubei-chan and Lyrical Nanoha are recognized for their magical girl stylings: an unwilling female protagonist, the wise sidekick who guides her as she takes her first steps into a larger world, and a mystical artifact that's the source of the heroine's power.
J2 and Nanoha A's are the epitome of sequels: the animation is slicker and the action sequences are much more elaborate. But be forewarned - while it is possible to enjoy the series on a purely superficial level, watching their respective predecessors will allow you to fully grasp the plot and see how these sequels improve on the original.
Jubei-chan 2 and Magical Girl Lyrical Nanoha A's are both magical girl series. Moreover, they are both unusual in that they aren't necessarily aimed at a female audience, as are most magical girl series. In addition, they both have superb action sequences and a protagonist who manages to reach out to many of her foes and show them the error of their ways. Both are also sequel series that have more elaborate action sequences than the originals, and feature far more badass protagonists.
Aikawa Maki, a high school student (with a reputation of being an exceptional street fighter), is known on the streets as Air Master. Standing at seven feet tall, she has the ability to seemingly fly through the air. Trying to attain the highest level of excitement and tension, she searches for stronger opponents. Will she find them or will they find her first, as they fight it out in the aerial arena?
Ten-year-old genius Chiyo, animal-loving Sakaki, loudmouth Tomo, athletic Kagura, weight-conscious Yomi and dim-witted Osaka are six friends who share laughs, good times, and a high school homeroom. With scary (and sometimes perverted) teachers, school festivals, penguin suits and general hilarity abounding, you can be sure that there's never a dull day in the life of one of these students!
Sousuke Sagara is far from the average high school student - not only is he highly trained in military tactics, he puts his knowledge to use in every single applicable situation (and even those nonapplicable ones.) So, when confronted with high school, he tends to turn average high school experiences into off-the-wall adventures. Love letters become terrorist threats and field trips become commando operations; his survival depends on the watchful eye of his best friend and classmate, Kaname. Together, they may just make it out of high school alive...
Youka, a thick-headed boy, has been forced into Zenshinkyou Temple to learn martial arts. During his short stay at the temple, he quickly decides that their style is not for him, and takes up an ancient martial arts style, Gyokujo Shinkei, under the beautiful female master Shouryuujo. Because of his oath to her, he has made an enemy of Ribakushuu, the evil sister of Shouryuujo, as well as the Zenshinkyou. After many years of training, a disaster of events occurs, and now a grown-up Youka must find Shouryuujo and a way to defeat Ribakushuu.