If you would like to do experience Onsen; hot spring wth seeing Mt. Fuji as a one day trip, come to Fuji View hotel.

It is a hotel and they offer hot springs for day-use visitors.
Fuji View hotel offers unrestricted panoramas of the majestic shape of Mt. Fuji from its front and provide very different surroundings at each time of year,  allowing you to enjoy the changing seasons in Japan.
In spring, more than 300 cherry trees bloom, providing views of Mt. Fuji rising behind a sea of blossoms.

The Fuji View Hotel is located in the Lake Kawaguchi Onsen Village.

You can relax in open-air bath and experience the wonders of hot spring as you create memories of your trip to Japan.

If you have time, with lunch plan available. They offer either Japanese-style or Western-style rooms to relax in as well.

【Fuji View Hotel】
Address: 511 Katsuyama, Fujikawaguchiko-machi, Minamitsuru-gun, Yamanashi
Tel: +(81) 555-83-2211
Open hours for day-use: 14:00~20:00
http://www.fujiview.jp/en/index.html

photo taken from official website.