The fleet of 51 11-car and 46 four-car trains will enter service from 2020 onwards, replacing series E217 EMUs on Yokosuka Line services from Tokyo to Kurihama and Tokyo - Chiba Sobu Line Rapid services.

The trains will be equipped with batteries to enable catenary-free movement in the event of a power outage.

The EMUs will also feature LED lighting, wheelchair-accessible toilets, CCTV, LCD passenger information screens, passenger Wi-Fi, and at-seat power sockets in Green Car accommodation.

JR East says standard seats will be 10mm wider than those on the existing series E217 sets.