This EMU is new generation series E231, developed by JR East. Power controller of series E231 is VVVF (Variable Voltage Variable Frequency) and TIMS (Train Information Management System) monitors and controls the EMU by computers.
Series E231 manufactured since 1999, 8 types are operating, type 900, 0, 500, 800, 1000, 3000, 6000 and 8000. In 2004, JR East has over 2000 cars and increasing in number to over 3000 cars untill 2007.