Teenage Mutant Ninja Turtles are four fictional teenaged superhero mutant turtles. Named after Italian Renaissance artists, they were trained by their rat sensei in the Japanese martial art of ninjutsu. From their home in the sewers of New York City, they battle petty criminals, evil overlords, mutated creatures, and alien invaders while attempting to remain hidden from society. During the peak of the franchise's popularity in the late 1980s and early 1990s, it gained worldwide success and fame.