A long time ago, there was a brother and sister who lived on the hill just above where the Aka tree stands today. The brother went to Ozato on an errand one day but he never returned. Rumors that the young man had been turned into a demon and was eating humans reached the village of Kinjo-cho.
His sister was very upset about the rumors so she decided to go to the village of Ozato to see if the stories were indeed true. There she found her brother and learned that he had really become an ugly and terrifying demon.
Sad and disappointed, she went back to Kinjo-cho but it wasn't very long before she realized that she was the only one who could stop her brother from eating other innocent victims. She devised a plan to betray his trust by making three mochi (rice cakes) to lure him back to Kinjo-cho. All three mochi looked the same from the outside but their contents were very different. The first rice cake was a regular mixture of pounded rice with some local herbs thrown in for taste. The other two, however, were filled with something else. One contained only nails while the other was stuffed with sharp pieces of broken clay tiles.
When the girl's demon brother arrived she laid out the moshi and immediately chose the one with the herbs. She bit into the cake and exclaimed how delicious it tasted. Her brother grabbed one of the remaining cakes and stuffed it into his mouth, but instead of the soft texture of mochi he found nothing but pain. His mouth filled with the taste of his own blood. The girl continued to eat her cake as if it was the most delicious cake to have ever been made. The demon brother then picked up the last of the three cakes and again his mouth felt pain. The more he chewed the more he tasted his own blood.
As he watched his sister finish eating her cake he noticed that she was sitting with her legs spread, revealing herself. Blood was dripping down her legs. The demon brother leaned back in astonishment.
"You are bleeding from your mouth down there," he exclaimed. "Why do I bleed from my mouth here and you from your mouth down below?"
The sister responded by asking, "What do you eat with your mouth, brother?"
"I eat humans," he said. He then looked at her, pointed, and asked, "And what about you? I see that you have eaten your mochi but what do you eat with your 'mouth' down there?"
The girl stared at him. "This mouth eats demons!" Hearing her words, her demon brother's face was filled with horror. He leaped backwards, but had not realized that the girl had sat him down just near the edge of a cliff - the same cliff that can be seen near the Oh Aka tree. The startled demon fell to his death.
Today mochi is still made and eaten every eighth day of the twelfth month of the lunar calendar to keep away demons. It is also said that the horn sticking out from the demon brother's head was buried at the site where the Oh Aka tree stands today.