construction of the line, which was initially called Toei Line 12 (都営地下鉄12号線, Toei Chikatetsu Jūnigō-sen). The first segment from Hikarigaoka to Nerima...

Rapid Railway Line 2 (名古屋市高速度鉄道第2号線, Nagoya-shi Kōsokudo Tetsudō Dai-ni-gō-sen), the western part, and Line 4 (第4号線, Dai-yon-gō-sen), the eastern part...