The Hakkaku tunnel is to be found at Misato village, south-east of Kumamoto city. The trains are no longer running, but this mysterious tunnel is a relic of the former railway line.
The Kumamen railway was built in 1915 to connect Minami-Kumamoto station with Misato. The Hakkaku (literally âOctagon Tunnelâ) was intended to protect the line from rockfalls and landslides in this mountainous region.
The roof and ribs of the structure are not completely closed as in a classic semicircular tunnel. In fact the tunnel is composed of seven octagonal rings open to the outside. The mysticism that surrounds the place has earned it the nickname âdoor to another dimensionâ or âtime machineâ.
A great mystery surrounds the reason for the octagonal shape so little used in this type of construction. Why did the engineers of the time opt for this steam-punk design worthy of a science fiction film? Nobody really knows the answer to that question.
Most see it as an attempt to reduce construction costs. Others think this was the most resistant shape to best protect trains passing underneath. Another hypothesis is simply that âit was the form of the concrete frameworkâ.
The line was abandoned in 1964, but 60 years later the tunnel is still standing.
The Hakkaku has become a ghost of Japanâs industrial past. The gothic atmosphere delights tourists discovering the site on social networks. Some marvel at the play of light within the tunnel, others are happy to be transported to âanother dimensionâ. If youâre already roaming Kumamoto, the moss-covered Kamishikimi Kumanoimasu shrine in Aso is another quiet stop, and the prefectureâs wider expanse of greenery and limpid water rewards a slower visit.
