Tokyo Metro is one of two rapid transit systems which make up the Tokyo subway system, the other being Tokyo Metropolitan Bureau of Transportation (Toei). This is the mostly used subway system in the world. The trains and stations are so clean and well maintained although some of the trains I believe are quite old.
Waiting for train at Minami Senju station. The train for Fukutoshin line (no 13). At Shinjuku station on M08. Clear signboard leading you for train transfer or exit. Tokyo Metro at "Meiji-jingumae". Tokyo Subway system map.