Akkorokamui is a gigantic red octopus of Ainu tradition, said to live in Uchiura Bay (also called Funka Bay or Volcano Bay) on the southern coast of Hokkaido, Japan. In the folktales it is large enough to swallow ships, and its red color is so intense that the sea and sky glow red when it appears.[1][2] It is a kamuy, a powerful being of the Ainu spiritual world, rather than simply an animal.
| Ainu name | Atkor kamuy, “the kamuy that holds strings” |
|---|---|
| Type | Being of Ainu folklore (a giant octopus kamuy) |
| Location | Uchiura Bay (Funka Bay / Volcano Bay), southwestern Hokkaido |
| Color | Bright red |
| Size in the tales | Spread over about 1 chō (roughly a hectare); one teller estimated 20 ken (about 36 m) |
| Key sources | Japanese folklore collections from 1914 onward, summarized in modern reference works |
The name
The Ainu people are the Indigenous people of Hokkaido and nearby islands. In the Ainu language, at means a string or strand, and the name atkor kamuy can be understood as “the kamuy that holds strings,” a vivid description of an octopus’s arms. John Batchelor’s Ainu–English dictionary of 1905 records a related word for octopus. “Akkorokamui” is the Japanese rendering of the Ainu name.[1][3]
The setting: a bay ringed by volcanoes
Uchiura Bay is a broad, nearly circular bay of about 2,500 square kilometers on the southwestern coast of Hokkaido. Its Japanese alternative name, Funka-wan, means “Eruption Bay,” and its English name has a similar origin. In September 1796 the Royal Navy commander William Robert Broughton charted it from HMS Providence while Mount Usu was erupting on its shore, and labeled it “Volcano Bay.” Several volcanoes line the coast, including Usu and Hokkaido-Komagatake. The bay is also rich fishing ground, with smelt, flounder, kelp and shellfish, and it is where Japanese scallop farming was first developed.[4]
That setting helps explain the legend’s imagery. A bay where the sky could glow red from eruptions, and where fishing families spent their lives on the water, is a natural home for a huge red creature that could be seen from far away and avoided.
Repun Kamuy and the Ainu sea
In Ainu belief, a kamuy is a spiritual being that can take many forms: an animal, a plant, a natural force or a household object. Animals in particular are often understood as kamuy visiting the human world in disguise, bringing gifts such as meat and fur and expecting proper respect in return. The bear is the most famous example, but the sea has its own powerful kamuy.[5]
The most important of these is Repun Kamuy, “the kamuy who lives in the sea,” usually identified with the orca. He controls the bounty of the ocean. In one myth he provides whale meat to a village and promises that the sea will protect its people from famine. The Ainu honored stranded orcas with ceremonies similar to those given to bears. It is Repun Kamuy who, in the best-known origin story, drags the giant spider Yaushkep from the land into Uchiura Bay and turns it into the octopus. Akkorokamui is therefore not a random sea monster. It is a dangerous being that a greater kamuy has removed from the land and placed where it could be watched and avoided, rather like the Welsh Afanc dragged to a remote mountain lake.[5]
What the tales say
- Its size. One folktale says that with its legs spread out it covered an area of about one chō, roughly a hectare. Another has a man named Itaknep estimate it at twenty ken, about 36 meters.[1] Because chō is also a unit of length, about 109 meters, the area figure is often misread as a length. This is probably the source of the “120-meter octopus” claimed on many websites.
- Its danger. It was feared as able to swallow a whole sailing cargo ship.[1]
- Its color. It was a vivid red that could be seen from a great distance, which gave boats a chance to steer clear.[1][2]
Origin stories
Two Ainu origin stories are recorded. In the better known, a giant spider called Yaushkep was ravaging the village of Rebunge. The sea god Repun Kamuy took charge of the monster and plunged it into the bay, where it became an octopus and lord of those waters.[1][2] In another tale, an octopus came from a goddess’s belt cast into the sea.[1]
Some modern sources say Akkorokamui is worshipped at Shinto shrines across Japan as a healing kami. That claim is poorly sourced and has been questioned, so we treat it as unverified.[1]
How big can a real octopus get?
The giant Pacific octopus is the obvious real model, and the actual figures are impressive enough. Adults usually weigh around 15 kg (33 lb) and can span up to about 4.3 m (14 ft) from arm tip to arm tip. Fishermen have reported much larger animals: one widely cited claim describes an octopus of 270 kg (600 lb) with a span of almost 10 m. Those reports come from the people who caught the animals and have never been verified. Each sucker on a large octopus can grip with considerable force, and the species lives three to five years, far longer than most octopuses.[6]
An animal that size, surfacing beside a small wooden boat and flushing dark red as octopuses do when disturbed, would make a lasting impression. Stretch it in the retelling to the size of a ship, and you have something close to the Akkorokamui of the folktales.
Real animals behind the legend
- The giant Pacific octopus. The North Pacific giant octopus (Enteroctopus dofleini), called mizudako in Japanese, lives in the cold waters around Hokkaido and is fished commercially there. It is the largest octopus species, with an arm span that can exceed four meters, and it turns deep red when alarmed. For people fishing from small boats, a large one would be an impressive sight.
- Giant squid. Giant squid have been recorded in Japanese waters, and the first photographs of a live giant squid were taken by Japanese researchers off the Ogasawara Islands in 2004. Stranded or floating squid may have added to stories of enormous many-armed creatures.
- Red water. The tales link the creature’s appearance to a red sea and sky. Sunsets over the bay or blooms of red plankton could have reinforced the image, though this is speculation.
Since 2019, Japanese law has formally recognized the Ainu as an Indigenous people, and in 2020 the national Ainu museum and park, Upopoy, opened at Shiraoi, on the Pacific coast east of Uchiura Bay. Stories like Akkorokamui’s are part of the living culture that these efforts aim to protect.[7]
Akkorokamui is not a cryptid in the sense of a reported animal awaiting discovery. It is a figure of Ainu belief whose story preserves a vivid picture of the sea around Hokkaido. For the European giant octopus legend, see the Kraken.
References
- “Akkorokamui,” Wikipedia, citing Yoshida Iwao (1914), Morino (1970), Sarashina Gen (1971), Chiri Mashiho (1973), the Nihon Mukashibanashi Tsūkan (1989), Aramata and Ōya (2021) and DeMello (2024).
- Matthew Meyer, “Akkorokamui,” The Night Parade of One Hundred Demons blog (5 May 2016). matthewmeyer.net.
- John Batchelor, An Ainu–English–Japanese Dictionary, 2nd ed. (Tokyo: Methodist Publishing House, 1905), s.v. “atkoro-guru.”
- “Uchiura Bay,” Wikipedia, and “William Robert Broughton,” Wikipedia.
- “Rep-un-kamuy,” Wikipedia, and “Kamuy,” Wikipedia.
- “Giant Pacific octopus,” Wikipedia, citing the Smithsonian’s National Zoo and W. L. High, “The giant Pacific octopus,” Marine Fisheries Review 38, no. 9 (1976).
- “Upopoy,” Wikipedia, on the National Ainu Museum and Park (opened 2020) and the 2019 Ainu Promotion Act.
Correction note (October 2026): This entry was rewritten from folklore sources. An earlier version said Akkorokamui was 120 meters long with 20-meter tentacles, could emit a blinding light and change its shape, controlled the weather, and was transformed into a deity by the goddess Takiribime. None of these details appears in the sources and they have been removed. The illustration above is an artistic impression.