Quoting Wikipedia's entry on Metropolitan Area Outer Underground Discharge Channel,

The G-Cans facility is also a tourist attraction and can be visited for free; however, as the tours are conducted in Japanese, a Japanese speaker must be present in the group to act as a translator for non-Japanese speakers.

I'd like to do this but can't find a lot of info.

For the Japanese speaker thing I was thinking maybe I could hire a translator (although I'm not sure how I'd go about doing that). But even if that's taken care of... at what times are the tours, what address do you go to, etc?

2 Answers 2


Their old English website (WBWM iFrame, click 'English' in the bottom right to view) seems to have gone (the last record the WayBackWhenMachine has is from February 4th this year)

However, after a bit of hunting it seems they have now moved to this address, which I only got by sticking '首都圏外郭放水路 見学会受付' into Google (the tour name, I believe). The site has everything in English (up until, of course, the actual application), but pasting the pertinent info below for posterity.

Tour Conditions

This tour is offered in Japanese language only. If you do not speak Japanese, bring along an interpreter with you; any people or groups that do not understand Japanese cannot participate in the tour for security reasons.

Participants must climb and descend about 100 steps by themselves in the tour of the surge tank

Able to confirm your application 30 minutes before the tour begins. Please get through confirming your application by the tour beginning time. It is not possible to participate in the tour when you are late for the tour beginning time.

From the viewpoint on safety, children aged 5 and under are not allowed, even though they are accompanied by their parent. Children aged 15 and under must be accompanied by an adult. (1 adult can accompany with children up to 5.)


Departs: Every Tuesday to Friday. 3 tours a day, max 25 people for each tour

1st tour 10:00 - 11:30

2nd tour 13:00 - 14:30

3rd tour 15:00 - 16:30

Applying for the tour

Once you've read the info at this page you can click the link at the end and apply (Japanese only).

Departure Point

The 2nd floor at Ryukyukan, Showa drainage pump station(Reception)

720 Kamikanasaki, Kasukabe city, Saitama 344-0111


Guide / Interpreter

Regarding guides / interpreters, take a look at the Japan National Tourism Office Guides / Interpreters section. You may be able to arrange something through them (or your hotel), or contact one of the volunteer groups by email / phone and try that way - please remember to only call during Japanese daytime GMT+8 :). If you can organise a few people to go you might be able to split the cost too.

  • The hotel I'm staying in doesn't provide interpreters but they did provide me with this link: jga21c.or.jp/index_e.html Maybe it'll help someone!
    – neubert
    Feb 19, 2014 at 4:42

This is a great question; I'm travelling to Japan next month and I'm tempted to add this to our itinerary. Codinghands did a great job of covering the basics. I read Japanese, so I can clarify some details.

There is an English-language overview of the Metropolitan Area Outer Underground Discharge Channel tour on the official website. It has links to sub-pages which give a lot of other information.

The tour starts from a building called the Ryukyukan (龍Q館), Showa drainage pump station. The address is 720 Kamikanasaki, Kasukabe city, Saitama 344-0111.

Getting there by train: from central Tokyo, take JR to Ōmiya, then change to the Tobu Noda line to Minami-Sakurai Station (南桜井駅). This should take just over an hour. From there it's 3km to the Ryukyukan, a 7-minute 1000-yen taxi ride or a 40-minute walk. Getting there by car: from the Tohoku Expressway's Iwatsuki Interchange, take Highway 16 towards Noda for about 17 km (30 minutes). From the Jouban Expressway's Kashiwa Interchange, take Highway 16 towards Noda for about 20 km (40 minutes). See the official Access Map for details.

The tours are 90 minutes long. About 10 minutes of that is in the "Underground temple", apparently. There are about 100 steps to climb. It is offered to ad hoc groups of 1-25 persons on Tues-Friday, at 10:00, 13:00, and 15:00, and to groups of 26-50 people on Mondays three times a day. The tour is in Japanese only, so each group with non-Japanese speakers must have at least one person who can translate safety instructions. If you come 30 minutes early, there is an 8 minute video in English which they can show.

Note that parts of the tour may be cancelled if, say, the tanks are full of floodwater. Children under the age of 5 are not allowed. Children from 5-19 years are allowed if accompanied by at least 1 adult per 5 children.

The tours are free, but prior reservations are required. The tour slots do fill up, so booking a few days in advance is helpful. You can book on the internet (Japanese language pages) starting 28 days before your desired tour time, ending 7 days before; or by phone on 048-746-0748 (in Japanese) from 28 days before to the day before. They want to you to arrive at the tour reception 30 minutes before tour time; latecomers will miss out.

For questions and to make reservations, call 048-746-0748 (in Japanese).

Other sources of information:

P.S. "首都圏外郭放水路 見学会受付" means "reception (desk) for the tour of the Metropolitan Area Outer Underground Discharge Channel". The term 見学会, which I translate as "tour", is ken gak-kai, or "see-learn-meet", which I think is a marvellously evocative term.

  • Great stuff, cheers for the clarification :) Nov 12, 2013 at 8:37

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