When Japan became a more peaceful, modern country in the 1800s, ninjas weren’t needed anymore. Although they had disappeared from the battlefield, ninjas stayed alive in people’s minds. Artists wrote about them in plays, comic books, and TV shows. The love of ninjas eventually spread to the US and other countries. Ninjas were used as the main characters in classic video games like Shinobi and Mortal Kombat. Their popularity continued to rise after the popular cartoon, Teenage Mutant Ninja Turtles, introduced ninjas to millions of children around the world.