...Shun claims to have uncovered a secret code that links a complex network of tunnels unknown to the general public. "Every city with a historic subterranean transport system has secrets," he says. "In London, for example, some lines are near the surface and others very deep, for no obvious reason."

Sitting on the Ginza subway from Suehirocho to Kanda, he says, you can see many mysterious tunnels leading off from the main track. "No such routes are shown on maps." Traveling from Kasumigaseki to Kokkai-gijidomae, there is a line off to the left that is not shown on any map. Nor is it indicated in subway construction records...

..."Subway officials treat me as if I'm a drunk or a madman," Shun notes with a wry smile. "Tokyo is said to have 12 subways and 250 km of tunneling. I'd say that last figure is closer to 2,000 km. It's clear to me that the tunnels for the Namboku, Hanzomon and O-Edo lines existed before decisions were made to turn them into public subways."