According to local Japanese belief, amabie is a mermaid-like yōkai with a mixture of human and fish features. It has long hair and a scaly body. It has a beak-like mouth, and three legs. It glows with a bright light that can be seen from the shore. They are auspicious yōkai — keeping a picture of an amabie can protect you from disease.

Little is known of the amabie’s characteristics. However, its story is very similar to other prophetic yōkai such as jinja hime and kudan, which deliver a prognostication and then disappear. These yōkai began appearing during a period when diseases like cholera were killing people all over the world. Images of protector yōkai that could be used as charms against sicknesses were in high demand. It is very possible that amabie was a sort of copycat yōkai, following the trends of the time.

The origin of the name amabie is a mystery. There is only one record of amabie in existence, and it appears very similar to another yōkai with a similar name: amabiko. There are numerous recorded amabiko sightings, and all of them are minor variations on the same theme: a three-legged creature that appears on the water to deliver a prophecy about abundant harvests and disease. Similarly, amabiko instructs people to spread its image around to protect them from the disease. "Amabie" may have been a simple typographical error, or else it may be a regional variation of the amabiko.

The only recorded sighting of an amabie comes from Higo Province (present-day Kumamoto prefecture) in April of 1846. For some nights in a row, a bright light could be seen in the waters off shore. One night, a government official went out to see to investigate the strange light. When he approached, a strange creature appeared to him. The creature introduced itself as an amabie. It told the government official that a six-year bumper crop was coming. It also said that should there be an outbreak of disease, he should immediately show the amabie’s picture to people everywhere, as it would protect them against harm. After that, the creature returned to the sea. Shortly after, the amabie’s story along with a woodblock print image of it was featured in the newspaper to be distributed to as many people as possible.