My husband and I climbed Mount Oku-Shirane, also known as Nikko-Shirane (日光白根山), this summer.
Starting from Yumoto Onsen (湯元温泉) it was a very long and extremely steep hike; however, the view from the top was truly spectacular and made us forget any muscle ache quickly! If you tackle this mountain from the Gunma side (Sugenuma or Marunuma Kogen, 丸沼高原スキー場), the climb is less strenuous; the views, however, are the same!