Two scenes of Momotaro: on the left, he entices a dog to join him; on the right, he poses triumphantly with the conquered demon. In the latter ningyo, a pile or cart of treasure, won from the demon, was probably originally part of the tableau. Note the difference between the babyish quality of the one boy and the more realistically proportioned adolescent of the other.
Here is a magnificent interpretation of Momotaro with his dog companion, depicted as a child courtier with a dog headress, on the website of the Maruhei doll company. Another Maruhei artist presented Momotaro as a young warrior triumphing over the demon and his three companions as warriors, each with a pose and details (colors, hair, emblems) invoking their animal qualities. In the late 19th century and the first decades of the 20th century, Momotaro was an important national and imperial symbol for the Japanese:  the child who "grows up fast" and takes dominion, just as Japan was a fast-growing  and powerful infant among nations.

A charming antique gosho doll of Momotaro with two of his animals (the monkey and dog) can be seen on the J.A.D.E.
site; it was part of a 2001 Metropolitan Museum exhibition of dolls from the collection of Michael Ayervais.