Nintama Rantarou

Comedical anime aimed at kids about kids who are ninjas. Frequent use of infantilized ninjutsu techniques. 

Episodical comedies about ninja childs and their hijinks. Both have similar artstyle and are long running shows with hundreds of episodes that are aimed at kids. 

Both are very long running anime aimed for kids witch child protagonists and their daily hijinks. Both don't have any main storyline and are episodical. The character design is similar. 

Follows the cast of children that are training to become ninjas, using combat and espionage techniques. Main difference is that while Nintama Rantarou is for kids, Naruto is for teens.