 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 gauge.The Setagaya Line and the Toden Arakawa Line (the only surviving line of the former Tokyo Toden network) are the only railway lines in Tokyo proper to be legally classified as tramways.The line has its own smart card system called Setamaru, which cannot be used on other Tokyu lines.