The local services of Chuo line and Sobu line are connectted together, operated just as one line.Originally Sobu line started from Ryogoku terminal, which is not connectted to Yamanote main circle line. In 1923, a new elevated line was opened from Ryogoku to Ochanomizu, and the direct operation has started. Where Keihin-tohoku line crosses Tokyo from south to northm, this line crosses from east to west. Series E231 was first introduces in this line, and spread many other lines. Slightly older 209-500 stocks are also in operation.