sentences:  The two-car sets (M201 to M205) were formed as follows.The E257-500 sub-series version was delivered between July 2004 and October 2005, with the first sets entering service from 16 October 2004 on Uchibo Line "Sazanami" and Sotobo Line "Wakashio" limited-express services, replacing older 183 series rolling stock.Based at Makuhari depot in Chiba Prefecture, the fleet consists of 19 5-car sets (NB01 to NB19).