The Kussie mass sighting at Lake Kussharo

Lake Kussharo sits in Akan-Mashu National Park, in Teshikaga, eastern Hokkaido. It is Japan's largest caldera lake. It covers 79.3 square kilometres and reaches 118 metres at its deepest.

It is also a hard place for anything to live. In 1938 the Kussharo earthquake released sulphur into the water. The lake turned acidic, around pH 4. Almost all the fish died.

Summer 1973. Most sources say August. Some say July. The exact day has never been found.

About 40 junior-high students from Kitami were on a mountain-climbing school outing to Mount Mokoto, on the lake's north-west rim. Japanese sources name the school as Kitami Municipal Kita Junior High School. Several accounts say teachers were with them. No student or teacher has ever been named.

The group looked down at the lake. Something was moving on the surface. Two humps. One Japanese account calls it something like a giant creature that appeared on the water, and says all of them saw it. English-language accounts give it a length of 10 to 15 meters, a giraffe-like neck and a mass on its back. Some add that it was a fast swimmer. It quickly crossed the lake.

So many people had seen it at once that newspapers and television across Japan took up the story. The press named the creature after Nessie. Kussie.

Other witnesses came forward. Japanese chronologies place a first sighting in November 1972, when a driver on the lakeside road saw something like an upturned boat moving toward shore. A forester hauling timber with his horse later reported a giraffe-like head 50 metres from shore; English sources date that encounter to July 1973, while Japanese ones say 5 July 1975. On 18 September 1974, about 15 people watched two triangular humps sink while moving about as fast as a motorboat. In 1997 Newsweek counted about 100 Teshikaga locals among the witnesses, including firefighter Yasuo Sugae, who described "a long, black, eel-like monster."

The cited sources provide no photograph or film of the 1973 school sighting. In September 1974 the broadcaster HBC spent about a month searching the lake with divers but found no firm evidence. Cryptomundo reports that fish-finder sonar picked up large images at depths of 15 to 20 metres. The cited sources describe no government investigation, and Newsweek reported that the town chose not to seek scientific checks. A spokesman explained: "It boosts tourism, making the lake more mysterious and full of fantasies and imaginations."

Sceptics return to the water itself. A lake with so few fish could hardly feed a large animal. In 2023 Professor Nakane Kenichi of Hokkai Gakuen University pointed to the monster boom of the 1970s, when children met monsters from television and film every day. Enthusiasts have proposed a plesiosaur, or Tullimonstrum gregarium. Earlier witnesses had already ruled out the obvious. A boat. A swimming horse.

Residents formed the Kussie Protection Association. Bihoro hotel owner Maekawa Ichijirō, credited by the Hokkaido Shimbun with lighting the spark of the legend, wrote the lyrics for "Nessie and Kussie," a 1976 single sung by Tanaka Seiji. A blue two-humped statue stands at Sunayu on the shore; at the craze's peak, Kussie brought about 200,000 extra visitors a year. In 2023 HTB identified association head Suzuki Kazuma, who says he has seen the humps twice himself. Kussie stands beside Issie of Lake Ikeda and Tossie of Lake Tōya among Japan's lake monsters.