Tucked away from the attention of the most travelers and even locals exists a barron lake west of Lake Chuzenji. That is also the name of the lake, West Lake or Lake Sai. The Kanji characters used for it's name are old. It isn't the same Kanji you see now for the direction of west.
You can get there via Senjogahara and Odashirogahara, or starting from Ryuzu waterfall via hiking through Senjugahama beach.
It's a little less than an hour to add Lake Sai to your hike from Senjugahama beach on Lake Chuzenji from Ryuzu waterfall.
It's a little over an hour added to your hike from the Odashirogahara moor past Senjogahara.
The following photographs are from 2 trips to the lake. There were recent bear sightings in the area and tried unsuccessfully to spot a bear on either trip. On the 2nd trip we started from Senjugahama beach on Lake Chuzenji.
Old Chuzenji village is in the far background on the opposite side of the lake.
the beach area makes a nice cove
leaving the beach toward Lake Sai are wood planks
From guests reports, this might have been where they saw the bears
There is essentially no grade change, about 100m in total, for most of the way from Lake Chuzenji to Lake Sai.
Certainly a great view of Nantai Mountain from inside the lake bed.