Better late than never: at Kudanshita Station next to Takebashi, the Toei Shinjuku Line and Tokyo Metro Hanzomon Line platforms were connected in March, so trains toward Shinjuku on the Shinjuku Line= left side of photo = and toward Oshiage on the Hanzomon Line= right side of photo = can now be reached from the same platform. In fact, all they did was remove the wall that divided one platform down the middle. Thanks to what some bestsellers called the "Wall of Idiocy," you used to go up stairs, through separate ticket gates, and down again to transfer — about 95 meters on foot, roughly one minute and ten seconds. That is now virtually zero. We were doing something absurd.
Typical bureaucracy — the harm of vertical silos — but along with removing the wall, other stations seem to be making transfer improvements like these:
① Make Hibiya Line Akihabara and Shinjuku Line Iwamotocho a transfer pair (70-yen transfer discount between Tokyo Metro and Toei)
② Allow free passage through platforms at Marunouchi Line / Namboku Line Korakuen and Mita Line / Oedo Line Kasuga to reach street level
③ Same for Namboku Line Ichigaya and Shinjuku Line Ichigaya
and so on. Free platform passage at Monzen-nakacho and Roppongi is reportedly planned for next fiscal year.
Many people must face this kind of inconvenience here and there. This is not a Tokyo Metro story, but I remember being annoyed when, exiting to street level from Toei Shinjuku Line Bakuro-yokoyama toward JR Bakurocho Station, I did not know a passage fee was charged to cross JR premises. On Odakyu or Keio, you can walk through the Shinjuku Station west exit connector to the east exit inside JR without any fee — or so I thought.