Oshino Hakkai, literally means the Eight Seas of Oshino, is a set of eight ponds in Oshino, a small village, located between Lake Kawaguchi and Lake Yamanaka. The eight ponds are fed by snowmelt from the slopes of Mount Fuji. The snowmelt is filtered down the mountain through porous layers of lava over a period of several decades, resulting in very clear spring water.
https://en.wikipedia.org/wiki/Oshino_Hakkai; https://www.gov-online.go.jp/eng/publicity/book/hlj/html/202301/202301_04_en.html;
Maps of Oshino Hakkai, Oshino-village, Yamanashi, 03/21/2024
Iris Pond (Shobuike), Sacred Place No. 8, Oshino Hakkai, Oshino-village, Yamanashi, 03/21/2024
Mirror Pond (Kagamiike), Sacred Place No. 7, Oshino Hakkai, Oshino-village, Yamanashi, 03/21/2024
Spring Pond (Wakuike), Sacred Place No. 5, Oshino Hakkai, Oshino-village, Yamanashi, 03/21/2024
Muddy Pond (Nigoriike), Sacred Place No. 6, Oshino Hakkai, Oshino-village, Yamanashi, 03/21/2024
Also, please refer to the articles on November 20, 2023 and April 10, 2018.