Just caught this on Ompuchaneru (http://rail-uploader.khz-net.com/index.php?id=37663)...
Work will start this year to prepare for the inclusion of 2 bi-level green cars in Chuo Rapid Line and Ome Line train formations. Additionally, the trains will be lengthened to 12-car formations. Based on the pdf, the bi-level green cars will be the familiar cars we see now in other Tokyo-area JRE consists. The service is planned to begin in 2020. This involves more than just building the cars; they'll have to improve stations, lines, signalling, and depots.
A little green car history fr