The story is a dramatization of the Japanese folklore legend of Momotaro, the Peach Boy, who with his trusted companions of dog, monkey and pheasant fought against evil in olden times.
The feudal lord Kisaragi Yae no Kami (Minami Komyo) searches for a child he had with a low-borne woman, that was sent away from his home 16 years ago while carrying a special seal. At that time, Kanda's detective Zenshichi (Ichikawa Kodayu II) had three daughters, the third of whom, Omiyo (Misora Hibari), was a skilled singer and an expert with the lasso.
Mariko studies at a missionary school in Shinshu. She drops out of school and joins her father on a circus tour when she discovers that her father, Ryutaro, whom she always thought was an agricultural and forestry engineer, was a circus clown. Over time, Mariko's singing attracted the attention of the public.
A young boy named Chomatsu (Misora Hibari) lives with an old man Denbei near the grounds of Asakusa temple as bell ringers. In their house is an Echigo lion mask, a memento of Chomatsu's deceased father. After several incidents of Echigo lion masks being destroyed in the area, a local kingpin Saheiji shows up at Denbei's demanded he hand over the mask, a request Denbei rejects out of pity for Chomatsu. However, after it is accidentally revealed that the mask contains an important map, Saheiji plots to steal the mask. Chomatsu gets involved after his mother makes a sudden reappearance that sends the boy on a roundabout journey that will reveal the truth about his family.