The spectacular landscapes of the alpine zone in the northern Hida Range (the northern Japanese Alps) , which can be accessed easily from the Tokyo and Osaka metropolitan areas, have enchanted many climbers. On the morning of 11 August 2005, a meso-scale (8000m³) rockfall suddenly occurred from a high cliff facing the Daisekkei (meaning a large patch of snow) Valley through which a large number of climbers access Mount Shirouma-dake (2932m) in the northern Hida Range; this resulted in one death and one injury. Although micro-scale (1-10m³) rockfalls are common in the Daisekkei Valley, the August 2005 rockfall event involved the largest volume of sediment since recorded history in the Shirouma-dake district. In the Daisekkei Valley, other geomorphic phenomena such as debris flows and supranival block slides are also serious threats to climbers. The elongated deposit with boulders in the photograph is of debris flow origin occurred on July 22, 2006.