Lake Biwa is the largest lake in Japan, and cycling around the lake is very popular.
It’s very close to Kyoto, and an e-bike can take you to the western end of the lake in 15km (1 hour).
You can cycle along the canal from Kyoto to Lake Biwa, or take a short loop to Omihachiman, the old center of Lake Biwa, and back, or even cycle 200km around the lake over three days.