The River Line

Hisatsu Line is mostly famous for its mountain part featuring a loop, two double zig-zag stations, and a 2,5 km long tunnel on the summit of Yatake mountain. Before the line's elevations reach as much as 30%, however, more than 50 kilometers of track can be found curving along the turns of the Kuma river. Some sources refer to this section as 'the River line', however officially it is the Yatsushiro-Hitoyoshi segment of the Hisatsu Line, which is still used for local passenger traffic.
The 'River line' features numerous bridges, small tunnels and galleries, as well as a variety of rolling stock including Kiha 185-series trainsets that were some time ago offered in N scale by MicroAce. It is also notable for its picturesque surroundings, small towns along the banks of the river, and the mountains that still dominate the whole landscape.
Both parts of the line feature stations and towns that are so small that they almost look like a model train layout.
Sakamoto Station

Sakamoto station is the third station of the Hisatsu Line. The station has two tracks and a wooden station building. Stop signs for freight trains led by the mighty D51-s are still preserved. The station was opened in 1908, and became unmanned after the electonic blocking was introduced in 1986. According to data collected in 2006, the station is used by 91 passengers daily.
This station was brought to my attention by the following photo posted by goagoa on Panoramio:
View full-size image

Click the link above for the full-size image, and you will see Sakamoto station with its complete surroundings, the Kuma river and, of course, the mountains. 

Impressed by the site's completeness and character, I have taken some time to count all the houses in the area surrounding the station. It turns out there are no more than 70 buildings at all. Fore one who would desire to model a complete station of a DMU-powered railway in Southern Japan, this is a very attractive prototype. Reducing the number of houses and the required length of track by what is called the selective compression, one would be able to reproduce the same picture by a modest amount of buildings and detail.

As far as operations are concerned, there used to be some freight traffic on this section of Hisatsu Line. Besides, according to Wikipedia, about 1 km away from the station there is an industrial branch, so there may still be an occasional movement of goods - no further information for these branches is available.

All station signs on the Hisatsu Line have an image painted on the station sign. The sign for the Sakamoto station features an observatory. One would never tell from the rural look of the neighbourhood that some serious scientific research is going on, however the place seems more than convenient for this type of activity.

Kyushu Choo Choo

A fine article under a fun title "Kyushu Choo Choo" (pdf) summarizing the available information about the Hisatsu Line and the Isaburo-Shinpei retro train was written by Beth Reiber and published in the American Chamber of Commerce Japan journal in 2006. Nothing presented is new, however it is a major step forward from trying to guess the same facts from Google Translate and not being able to understand half of what is meant by the original texts.
I'm also presenting here my favourite Hisatsu Line wallpaper, published on Panoramio by goagoa. Its colors, harmony, and composition have been inspiring me for nearly half a year. 

http://www.panoramio.com/photo/11093079

This photo shows the feel of the remote station of Masaki, featuring another double zigzag arrangement of the Hisatsu Line. The trains appear from the right side (where the Yatake summit and the Okoba station are), come to a halt in the upper left part on a stub track hidden by the trees, then reverse to the station and continue to the lower part again hidden from view here.
Masaki area was heavily populated and had even some amount of freight operations (Station Staff, last photo), however, after a series of devastating landslides culminating in a massive landfall in 1972 when approximately 300 000 square meters of earth slid from their place and destroyed several dozens of houses, the population moved away, leaving the area deserted. The station however continues to operate. To commemorate the massive amount of work in order to restore the line after the landslide, a 8-ton boulder was left on the platform.
The Masaki station would make a tremendous small layout in N scale, however, proficiency in landscaping may be required to reproduce at least some of its remarkable features.