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Hakkaku Tunnel Kumamoto – Hidden Octagonal Railway Tunnel in the Forest

Hakkaku Tunnel Kumamoto – Hidden Octagonal Railway Tunnel in the Forest
Hakkaku Tunnel in Kumamoto is a little-known relic of the former Kumaen Railway, built as an octagonal rock-shelter along the line. This guide explains the tunnel’s unusual eight-sided structure and history, photogenic spots where light and shadow create a mystical atmosphere, nearby walking paths in nature, how to get there and parking, plus safety tips for travelers who enjoy quiet off-the-beaten-path places.

Highlights

Hakkaku Tunnel (Octagonal Tunnel) Overview

The Hakkaku (Octagonal) Tunnel is a remnant of a rockfall shelter from the former Kumaden Railway, known for its octagonal design and secluded, “hidden spot” atmosphere.

Hakkaku Tunnel Structure

With its rare octagonal layout, you can experience the geometric structure up close as you walk through.

Hakkaku Tunnel History

The Hakkaku Tunnel is one of the remains associated with the former Kumaden Railway, which once linked Minami-Kumamoto and Toyo (now Misato Town), and preserves a facility built as a rockfall protection shelter.

Hakkaku Tunnel Access by Car

It’s in Komushiro, Misato Town (Shimomashiki District), Kumamoto Prefecture, about a 25-minute drive from the Kyushu Expressway’s Matsubashi IC. From the parking area near Futamata Bridge (about 10 spaces as a guide), it’s a short walk.

Hakkaku Tunnel Access by Bus

From Sakuramachi Bus Terminal, take Kumamoto Bus and get off at “Futamata Bridge” or “Komushiro,” then walk about 10 minutes (service may be limited, so checking in advance is recommended).

Hakkaku Tunnel Admission and Parking

Admission is free, and there is parking around the tunnel (capacity is approximate).

Hakkaku Tunnel Walking Tips and Cautions

The tunnel can be slippery depending on conditions, so sturdy shoes are recommended, and there are few toilets in the surrounding area.

For the latest information, please refer to official announcements or check on site.

What Is the Hakkaku Tunnel? An Industrial Heritage Site from the Old Yūen Railway

The Hakkaku Tunnel is a remnant of the former Yūen Railway in Misato Town, Shimomashiki District, Kumamoto Prefecture, and is gaining popularity as a hidden sightseeing spot.

The row of concrete structures with a distinctive octagonal cross-section is a photogenic place that combines historical value with a mysterious atmosphere.

Strictly speaking, it is not a tunnel but a rockfall-protection gallery (shelter) built for a cut section.

Its unusual shape and the quietness of the abandoned railway site captivate visitors.


Highlights of the Hakkaku Tunnel

1. Mysterious Octagonal Structure

The biggest feature of this tunnel is its unique octagonal cross-section.

This design, different from the horseshoe shape seen in ordinary tunnels, is considered rare even in Japan.

There are several theories as to why it is octagonal.

About seven octagonal concrete frames are lined up in a row, and gaps between the frames let in dappled light in the morning and evening, creating a magical atmosphere.

2. Historical Background of the Yūen Railway

The Hakkaku Tunnel is one of the remains of the Yūen Railway, which once connected Minami-Kumamoto Station in Kumamoto City to Tomochi Station in present-day Misato Town.

The Yūen Railway opened in 1915 (Taisho 4), and there was once a plan to connect Kumamoto with Nobeoka in Miyazaki Prefecture, but it was never realized.

Even after the line was discontinued in 1964 (Showa 39), this gallery remained and is cherished as a valuable industrial heritage site.

After the railway was abolished, the company renamed itself Kumamoto Bus and still operates bus services today.

3. Nature in Every Season

Rich nature surrounds the tunnel area.

Seasonal scenery such as fresh greenery in spring (April to May), cool views wrapped in lush summer trees, autumn leaves (mid to late November), and winter quietness further enhances the tunnel’s charm.

The contrast between moss-covered concrete and the surrounding greenery is especially beautiful, making it a highly photogenic spot.

4. The Tunnel’s Mystical Atmosphere

Inside the tunnel, cool air and quietness with dappled sunlight create a mysterious atmosphere.

The light shining through the gaps in the frames changes depending on the time of day and weather, so you can enjoy different views each time you visit.

Away from the bustle of the city, you can relax in the silence and nature unique to this abandoned railway site.


Access Information

  • Location: Komushiro, Misato Town, Shimomashiki District, Kumamoto Prefecture
  • How to Get There:

By car: About 25 minutes from Matsubase IC on the Kyushu Expressway.

Walk from the parking area near Futamata Bridge (about 10 spaces).

About 30 minutes from Mifune IC.

Public transportation: Take a Kumamoto Bus from “Sakuramachi Bus Terminal” in central Kumamoto City, get off at “Futamata Bridge” or “Komushiro” bus stop, and walk about 10 minutes.

  • Parking: Parking spaces are available near the tunnel (about 10 cars). Vehicles are not allowed beyond the parking area, so you must continue on foot.
  • Admission: Free
  • Time required: About 30 minutes for the tunnel alone. About 1 hour if you also stroll around nearby Futamata Bridge.
  • Best season to visit: Fresh greenery in April to May and autumn foliage in mid to late November are recommended. In summer, bring insect repellent because there are many mosquitoes.

Nearby Highlights

Futamata Bridge

“Futamata Bridge,” located a 2- to 3-minute walk from the Hakkaku Tunnel, is a stone bridge spanning the confluence of the Shakain River and the Tsuru River.

Around noon from November to March, sunlight shines through the bridge arch and creates a heart-shaped shadow, which is what it is known for.

Stone Bridges of Misato Town

Misato Town is home to many stone bridges built from the late Edo period to the early Meiji period.

A stroll visiting historic stone bridges such as Reidai Bridge is also recommended.

Why Visit the Hakkaku Tunnel?

Popular Photo Spot

With its distinctive shape and beautiful natural surroundings, the Hakkaku Tunnel is an ideal photography spot for photographers and travelers.

Especially in the early morning and evening, when light shines through the gaps in the frames, it has become a hot topic on social media for its dreamlike photos.

A Hidden Off-the-Beaten-Path Spot

It is a place with relatively few tourists, where you can spend quiet time.

It is perfect for people who want to avoid crowds and enjoy the atmosphere unique to an abandoned railway site.

Experience Local Culture

Around the Hakkaku Tunnel, you can enjoy touring Misato Town’s stone bridges and bathing at Samata Onsen.

There are also eateries where you can try local sweetfish dishes and handmade soba, making it a great opportunity to experience local culture more deeply.


Traveler Tips and Summary

Useful Tips

  • What to bring: Wear comfortable walking shoes. The old railway track area near the tunnel is unpaved, and the ground can get muddy after rain.
  • Notes: There are no restrooms near the tunnel. Please use the restroom at the Futamata Bridge parking area in advance. Also, be careful not to get too close to the structure because of the risk of falling rocks.
  • Local food: Salt-grilled sweetfish raised in the Midorikawa River basin in Misato Town and local handmade soba are recommended. You can enjoy them at eateries near Samata Onsen.

Summary

The Hakkaku Tunnel is a special sightseeing spot where the nature of Misato Town, Kumamoto Prefecture, harmonizes with the history of industrial heritage.

Through its mysterious octagonal gallery, it conveys the legacy of the Yūen Railway, which supported people’s lives from the Taisho to Showa eras.

If you visit it together with nearby Futamata Bridge and the stone bridges, you can fully enjoy the charm of Misato Town.

Be sure to add the Hakkaku Tunnel to your Kumamoto travel itinerary.



Frequently Asked Questions

A. The Hachikaku Tunnel is an octagonal rock shed built to protect the former Kumayen Railway track from falling rocks. Its unusual shape appearing suddenly in the forest makes it a popular photo spot. Around midday, when light enters, shadows create depth—using a wide-angle lens to emphasize perspective adds atmosphere.
A. The Kumayen Railway was a private line that connected Minami-Kumamoto Station and Toyo Station (around today’s Misato Town area), with a total length of about 28.6 km. Even after closure, remnants like bridges and tunnels remain scattered. The old trackbed can get muddy, so grippy shoes are safer than regular sneakers.
A. By car, it’s easiest to follow signposts from central Misato Town toward the site. Some sections are narrow, so leave extra time in case you need to yield. Parking space is limited, so avoid stopping on the road and use only safe, designated places where you can park.
A. If you’re mainly taking photos, 15–30 minutes is a good guideline. In the morning and evening, long forest shadows can create a “Ghibli-like” vibe, but low light increases blur—your phone’s night mode can help. Weekday mornings tend to be quieter, making it easier to shoot without people in frame.
A. There are almost no streetlights, so at night it’s hard to see your footing—shooting in daylight is recommended. After rain, wet leaves can be slippery, and moss can be slippery if you step on it, so take care. If you use a tripod, set it where it won’t block the path and be considerate so taking photos doesn’t cause issues.
A. A good approach is to shoot from the entrance side, keeping the center line in mind to build a symmetrical composition. Puddles on the ground can create reflections, so a lower angle can look especially magical. If you include a person, have them stand deeper inside to convey the scale of the octagonal structure.
A. The Misato Town area has many stone bridges and riverside scenery, making it a good place for “railway-remnant” style exploration alongside Hachikaku Tunnel. A satisfying flow is photos → a short walk → a hot spring stop. Some mountain roads have weak reception, so saving maps offline in advance is reassuring.
A. Because these remnants are preserved and can be fragile, the basic rule is not to enter fenced-off or restricted areas. Graffiti is absolutely not OK, as it seriously damages the scenery. Bring insect repellent and water, enjoy the quiet forest atmosphere, and aim to finish shooting efficiently in a short visit.

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