Wow, what a great thread! So much good info, pics and vids.
There is some recently made public video footage of Japan's first ever "permanently installed" roller coaster, called "陸上波乗" (Rikujyo Naminori / "Land Wave Rider"). The footage was taken sometime in the 1930s:
The roller coaster was in the shape of a boat, and just went around in a large oval, while going up and down some very small bunny hills. It was installed at an amusement park called "Tamagawaen" in 1925. I'm not sure how long the coaster operated for, but the park closed down in 1979.
Here is a map of the park sometime in the 1930s to very early 1940s:

Also, a picture of the ride:
In case you were wondering what Japan's first *ever* roller coaster was, it was a temporarily installed (in 1890) roller coaster in Ueno called "自動鉄道" (Jidou Tetsudo / "Automatic Railway"), It was installed for the "第3回内国勧業博覧会" (3rd Domestic Industry Expo).
I haven't found any pictures of it, but there are a few drawings of it here:
http://blog.livedoor.jp/misemono/archives/51898407.html
On another note, there were pics of the following coaster earlier in the thread, but here is a somewhat odd video of the "Giant Coaster" that used to be at Fuji-Q Highland.
Skip to 07:00 to see the start of the coaster leaving the station.
I'm not sure if I've ever seen an escape artist trying to "escape" from a roller coaster while it is on fire before...
The video was originally shot in 1973 (later rebroadcasted many years later, which is why you hear Indiana Jones music), and the escape artist's name is a famous person from Japan called "Hikita Tenko".