[2] The Setagaya Line was opened by the Tamagawa Electric Railway (玉川電気鉄道, Tamagawa Denki Tetsudō, "Tamaden") in 1923, running on surface streets between Shibuya and the Tama River.

Since the railway merged with Tokyu in 1938, the balance of the line closed in 1969, leaving this isolated section as the sole Tokyu line to use 1,372 mm (4 ft 6 in) gauge.

In March 2007 the PASMO contactless card has also been accepted on the Setagaya and other Tokyu lines.

The smart card system was abolished and merged with PASMO in 2012.

Although most of the line was closed due to it running on roads, causing traffic congestions, Setagaya line barely had any sections running on roads, contributing to it staying open.