How to travel through Tokyo’s Yamate Tunnel

I hear the Yamate Tunnel on the Central Circular Route (C2) of the Shuto Expressway is one of the longest road tunnels in the world. I'm trying to figure out what is the easiest way I can see it without having to get a rental car myself.

This video shows somebody riding a bus that takes the tunnel route:
https://www.youtube.com/watch?v=7hV2ysXDZkI

Is there anyway I can track down which bus routes run through the tunnel? I don't really care about start and destination. I can take the subway from wherever I end up.

Do taxi drivers ever like to use this tunnel?

Hello.
There are no buses that run through all the route of Yamate tunnel ,but airport limousine bus runs through a part of the tunnel .
You can see the tunnels part from Oi to Ohashi by taking airport limousine bus from Haneda to Shinjuku.

No regular tunnel watching tour and local line bus.
Air port Limo bus of HND are better right
http://www.limousinebus.co.jp/en/
from/to Ikebukuro is ride longer than Shinjuku but not big different
and no run both thru Ohashi junction loop tunnel(to/from Tomei Exp-way) section.
http://www.shutoko.jp/ss/tokyo-smooth/ohashi/ohasi-summary.html
http://www.shutoko.jp/ss/tokyo-smooth/about/yamate-safety-detail4.html

This is new section(9.4km) inside reports before open. (Use google translate)
http://portal.nifty.com/kiji/150227192868_1.htm
https://youtu.be/P19v5a-Zfps
https://youtu.be/6l6BoiwsU4A

By taxi easiest but just not cheap
if only thru full tunnel section over 18km in/out nearest exit
need over 6000Y(around 30min) if no traffic jam or other cars accident.

If u have "IDP" rent a car(self driving) recommend.
https://youtu.be/j3Qk_VzfHxU