Sosbun Brakk. Sosbun Brakk was unclimbed although it had been attempted by Germans in 1976. We climbed it by the southwest ridge to the headwall, below which we traversed right to gain the upper slopes. Our expedition consisted of Hisao Hashimoto, Mikio Tabata, Norichika Matsumoto and me as leader. We established Base Camp at 14,700 feet south of the peak on June 14. Camps I, II, III, IV and V were pitched at 16,400 feet (at the foot of the ridge), 17,450, 18,300, 18,625 and 19,900 feet on June 17, 21, 24, 26 and 28 respectively. The weather was bad on July 1 and 2. On July 3 Hashimoto and Matsumoto set out for the top, bivouacked at 20,375 feet and reached the summit (6413 meters, 21,040 feet) at 11:23 on July 4. They descended a more direct line down the south face.
Seiichi Kawauchi, Japanese Alpine Club