▁fifth - batch ▁ 3 0 0 0 ▁V ▁series ▁six - car ▁set ▁entered ▁service ▁on ▁the ▁line ▁on ▁April ▁ 9 , ▁ 2 0 1 7 , ▁with ▁a ▁total ▁of ▁seven ▁sets ▁scheduled ▁to ▁be ▁introduced ▁by ▁ 2 0 2 2 , ▁replacing ▁the ▁earlier ▁ 3 0 0 0 A ▁series ▁train sets . ▁ ▁Form er ▁▁ 1 0 0 0 ▁series ▁ 1 4 ▁x ▁ 6 - car ▁EM Us ▁( from ▁December ▁ 1 9 7 2 ▁until ▁November ▁ 2 0 0 6 ) ▁▁ 2 0 0 0 ▁series ▁ 9 ▁x ▁ 6 - car ▁EM Us ▁( from ▁ 1 9 8 4 ▁until ▁November ▁ 2 0 0 6 ) ▁ ▁History ▁ ▁In ▁ 1 9 6 5 , ▁construction ▁on ▁Line ▁ 1 ▁and ▁Line ▁ 3 ▁of ▁the ▁sub way ▁began . ▁The ▁sub way ▁was ▁inaugur ated ▁on ▁September ▁ 1 6 , ▁ 1 9 7 2 , ▁when ▁the ▁ 5 . 2   km ▁long ▁initial ▁section ▁of ▁Line ▁ 1 ▁opened ▁between ▁K ami - Ō oka ▁and ▁I se zak ich ō j am achi ▁stations . ▁On ▁September ▁ 4 , ▁ 1 9 7 6 , ▁Line ▁ 1 ▁was ▁extended ▁in ▁both ▁directions : ▁ 2 . 8   km ▁and ▁ 2 ▁stations ▁to ▁the ▁south west ▁( from ▁K ami - Ō oka ▁to ▁K amin ag aya ), ▁and ▁ 0 . 7