From the trailhead of Mt. Kuromatsunai toward the summit, you can get there in about 15 minutes. It's open, so the sun shines in and it was a bright waterfall. As a slide waterfall (nametaki) in Hokkaido it's on the larger side and well worth seeing. It's also the route from here for stream climbing (sawanobori) to the summit. I'm not sure whether the waterfall's signboard is still there.

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Park your car at the parking lot near the entrance of the Mt. Kuromatsunai trail, and after walking about 100 m you'll see Buna Falls, and after walking about 500 m further you'll see Omotaki Falls.