Sekai Ninja Sen Jiraiya was a Japanese tokusatsu television series from the late 1980s, following a young ninja who battles sorcerers and rival clans with the help of a suit of mystical armour. Its opening theme became closely linked to the hero himself, and the series later found an especially devoted audience outside Japan, where reruns and fan edits kept the music alive. Today creators reuse the theme as shorthand for retro heroism, nostalgia and old-school action television.