In what year did the eruption occur that laid down the lava upon which a famous forest visible from the Tenjō-Yama Park Mt. Kachi Kachi Ropeway? 
Tenjō-Yama Park Mt. Kachi Kachi Ropeway: The Tenjō-Yama Park Mt. Kachi Kachi Ropeway (天上山公園カチカチ山ロープウェイ , Tenjōyama Kōen Kachikachiyama Rōpuwei ) , officially the Lake Kawaguchi Mt. Tenjō Ropeway (河口湖天上山ロープウェイ , Kawaguchiko Tenjōyama Rōpuwei ) , is a Japanese aerial lift line in Fujikawaguchiko, Yamanashi, operated by Fuji Kyuko. Tenjō-Yama Park Mt. Kachi Kachi Ropeway:  The observatory has a view of the lake, as well as Aokigahara forest, and Mount Fuji.
i don't know