主角小灵精是一名修行中的少年忍者,从伊贺到东京,寄居在三叶家中所发生的故事,并描写小灵精与男孩健一的友情等,也介绍(或创作)了不同的忍术。由于忍者出现在现代社会,引来各式各样的骚动,内容轻松风趣,设合藤子不二雄一直以来“少年遇上不可思议的人物”之公式故事。Hattori a ninja boy who has come from the Iga mountains is now a part of the Mitsuba family along with his brother Shinzo and his ninja dog. Hattori helps Kenichi with his problems and constantly keeps an eye on him as a good friend.