This is a film version of "Son-goku the Monkey," but featuring a set of new characters. It is considered to be among Tezuka Osamu's monumental works because it represented his first full-scale animated piece, created through a process of trial and error in pursuit of his childhood dream of creating animation film. For this work, however, he was only in charge of the original story and storyline. He was not yet involved in drawing. He intended to create a tragic ending in which Son-goku's sweetheart dies, probably because he wanted to express one of his major concepts that "man should overcome loss and face the future, learning from even the worst of situations." Tezuka Osamu might have wanted children to learn the importance of "life and death" through this kind of ending. However, Tezuka Osamu's plan was altered because Toei Animation preferred a happy ending for its entertainment value. This incident might have taught Tezuka Osamu, who was just beginning his career as an animation writer, that he needed to use his own resources in order to express his true opinions.