Nintama Rantarou

Taking place in the Sengoku Period, Rantarou, Kirimaru and Shinbei are young students at Ninjutsu Academy, a school that teaches all kinds of youth how to become ninjas. Known as "Nintamas" (a contraction of ninja + tama [egg]), the main trio, and many other students at the school, must learn all sorts of unique skills to achieve their goal. Unfortunately, things aren't that simple, since our protagonists constantly find themselves failing their classes. With strict ninja teachers such as Doi-sensei and Yamada-sensei, the mischievous girls from the Kunoichi class, an entire crew of pirates and dozens more interesting characters, anything can happen in the crazy world of Nintama. The episodes are 7 minutes and thirty seconds long each, and each season (which there's currently 29 of) usually has a range of 60-90 episodes.