The story of Momotaro is one of the most popular folktales in Japan. Of course, there are many variations, but the basic story goes as follows.
A long time ago, there was an old couple living in a remote place. They had no children and were lonely. One day, as the woman was doing laundry, a giant peach came floating down the stream. She hauled it out of the water and brought it home.
The old couple was just about to start eating the peach when suddenly it split in two to reveal a young boy, claiming he had been sent by Heaven to be their son. They named him Momotaro (after momo, meaning “peach”, and Taro, a popular boy’s name) and raised him lovingly. He practiced fighting, and grew up to become powerful, as well as kind.
Then he was told about demons from Onigashima (“Ogre Island”), who had been tormenting the people of the countryside. Though they were concerned at first, he convinced his parents to let him go and defeat the demons. The gave him some millet dumplings and off he went.
On the way, he met a dog, a pheasant, and then a monkey, who all asked him what he was doing. He told them about his quest, and that he had the best millet dumplings in Japan, which he would share if they accompanied him. They agreed, and he gave them each a dumpling.
Momotaro and his entourage reached Onigashima. Fueled by the dumplings, they fought off all the oni, until their leader begged him to stop. Momotaro and his companions left with a boat loaded with the treasure stolen from the villages the oni had raided, in exchange for letting the oni go in peace with a promise never to trouble humans again.
Although Momotaro’s story was ditched in the final version in the game, it’s thanks to him that we have the wonderful dungeon based on Onigashima, Oni Island. Remnants of this story still appear in Momotaro’s design and his subquest: the split-peach pants, monkey nose, pheasant headdress and wings, and the quest to retrieve his stolen Millet Dumplings from Hayazo. He likes to march around pretending to defeat the demons of Oni Island, and asks you—the dog—to play with him, offering his Millet Dumplings in return. He’s not quite as polite as his legendary counterpart, however.
The sign on his back reads “one kill a day”.
Onigashima is typically associated with Megijima, and island north of Takamatsu on Shikoku, whose summit is riddled with manmade caves where the oni were said to live. Okami’s Oni Island may be based on its depiction in the 80’s Famicom game “Shin Onigashima” (New Onigashima).