After the arrival of the 221 series in the Keihanshin region, the maximum speed of special rapid trains was increased to as of the March 10, 1990, timetable. That year, all 117 series cars underwent improvement to their brakes to accommodate this new operating speed. As new 221 series cars entered service, there was an excess of 117 cars, and as the speed of most special rapid services was further increased to , 117s were reassigned to other lines. The 300 subseries entered service on the Fukuchiyama Line, while shortened consists began running on the Nara Line, Kosei Line, Kusatsu Line, and on the Sanyō Main Line in the Okayama area on the Sunliner service. Cars which became surplus due to the use of shorter configurations were converted into the 115 series 3500 subseries. This was the first reduction in the number of 117 series cars.
