Original: Tokyo 's northernmost and westernmost points lie in Okutama , as does Lake Okutama , an important source of water for Tokyo , situated above the Og chi Dam in the town .
Simplified: Mount Kumotori , Tokyos highest peak at 2017 m , divides Okutama from the Okuchichibu region of the neighboring Saitama and Yamanashi Prefectures .