The monster was first observed in 1961. In 1978 the story started to be taken more seriously when the 20 attendants of a memorial service testified that they saw the monster. In the September 3rd 1978 encounter Yutaka Kawaji and his relatives were at the lakeside .Kawaji’s children Hiroto, Mutsumi and Tomoko were playing by the lake shore when they noticed two humps belonging to a large black creature in the lake. The humps measured five metres (about 16 feet ) and stood 60 centimetres (two feet) out of the water. The children shouted to the others present and Yukata Kawaji leapt aboard a motorboat and pursued the creature as it crossed the lake going quite fast. He was unable to catch up with the creature but the sighting lasted three to four minutes, and he said he was able to see the humps twice for about 20 seconds.
Then the creature was apparently photographed on December 16 1978 by Toshiaki Matsuhara. It was 1.30pm when Matsuhara saw a whirlpool suddenly appear in the middle of the lake. For five minutes he watched it through a 50X telescope as it moved northward before it disappeared. While scanning the lake in the aftermath of his initial sighting Matsuhara’s attention was drawn to a moving object . He quickly took a series of photographs and in one of them what appears to be two humps with spinal ridges can be seen. When the photos were published, Yutaka Kawaji contacted the tourism department to say that Matsuhara had photographed the creature he had seen three months earlier and that it was also in the exact same location off a local landmark known as the Couple’s Rock.
In January 1991, another visitor at the lake took video footage of a creature, approximately 30 ft. in length.
The lake is home to eels up to 2 metres long (about 6 to 7 feet). It is conceivable that Issie could be a giant eel. The questions are of course, is there more than one and how did they get that big?
Video of the lake: http://www.youtube.com/watch?v=zFub7eIsXQA