Trailhead to Minami Alps. You can stay here overnight. I generally use this place to wash up after my hike.
HP: https://en.mountaintrad.co.jp/~aokikosen/

About:

Aoki Kosen is a hot spring located in Yamanashi, Japan. It offers a relaxing and rejuvenating experience for visitors looking to unwind and soak in the natural beauty of the surrounding area. With its soothing waters and tranquil atmosphere, Aoki Kosen is the perfect spot to escape the hustle and bustle of everyday life and enjoy a peaceful retreat in nature.

Business period
・ GW period: Every day from April 27 to May 6, 2024
・Friday, Saturday and Sunday from May 7th to July 18th, 2024　
・Summer season: Every day from July 19th to August 25st, 2024
・Fridays, Saturdays and Sundays from August 31st to October 20th, 2024