Ichijoudaki [一乗滝] is a 12 meter high waterfall in the mountains of Fukui prefecture--near Fukui City and Sabae.
In the summer, it is a hot spot for people to go to cool down. Being deep in the mountains alone cools the air, but standing near the waterfall gives an extra refreshing spray of cool water.
There are two nearby parking lots and if there aren't many people, you can drive pretty close to the waterfall. Additionally, there are nice, new restroom facilities and a place to have a picnic nearby.
In short: it is second only to the library for a place to hideout during the long, hot August month.
Tradition has it 佐々木小次郎 (Sasaki Kojirou) the arch-enemy of 宮本武蔵 (Miyamoto Musashi) practiced his 燕返し tsubame kaeshi (Kenkyusha has the definition as: 'a quickly reversed cut' whatever that means) fencing movement at the base of the waterfall while the water belted him from above. I suppose this was to improve concentration with distractions.
Who knows if this is true, but it makes for a good enough story to have a statue of the famous samurai near the waterfall. (see left).
I didn't know this, but according to Wikipedia, Sasaki was born in Fukui Prefecture (Yumi's hometown)! It has to be true since it came from the Internet. (Of course the Onion did once report of a Factual Error Found on the Internet regarding a Brady Bunch fan site, but I believe it has since been corrected)
Apparently, they filmed some of the NHK 大河ドラマ「武蔵 MUSASHI 」 in Fukui.
Links on 一乗滝 (in Japanese)