There was an avalanche involvement and full burial of 1 snowboarder in the Mumeisawa basin off the Happo North side. The slide was apparently self triggered from a step east facing open slope with a few sparse trees at 2050 m. The victim was carried an apparent 600 m or so down the tight valley at the base of the Mumeisawa basin to his burial point at approximately 1750 m.
Thanks to some quick action by close bystanders and members of the injured recreationalist's party the victim who was fully buried was located and dug out of the debris with in less than 15 minutes. Once the victim was uncovered and treated for shock the very lucky and thankful crew waited for Nagano Mountain Police Rescue to arrive by helicopter. On the Police helicopters swift arrival the victim was hoisted and then flown to hospital by helicopter.

Tests on the snow pack and investigation (at a distance) of the accident site found the following:

Crown fracture; 20 - 60 cm deep (observed from a distance)‚ was a width of 100 m and the terminus of the deposit was 600 m below the start zone.

Tests near the incident on eastern aspect at the same altitude in the Happo Ike area found weakness at the new and past snow interface at around 30 cm below the surface. below that that the snow pack was settling and grains are rounding and increasingly strength. Compression tests found moderate sudden collapses at the 30 cm layer and moderate resistant planer down 50 cm from the snow surface.