The Japanese maglev train series that set a record of 603 km/h is the L0 Series.
The record was achieved by a manned, seven-car L0 trainset operated by Central Japan Railway Company (JR Central) on the Yamanashi Maglev Test Line on 21 April 2015. It sustained 603 km/h for about 10.8 seconds, reaching the speed roughly four minutes into the run.
The L0 uses Japan’s superconducting maglev, or SCMaglev, technology. Its vehicles levitate above and are guided along a dedicated guideway rather than running on conventional steel wheels. JR Central developed the series for the planned Chūō Shinkansen, intended eventually to link Tokyo, Nagoya and Osaka.
A common mix-up is MLX01, the earlier Japanese maglev that reached 581 km/h in 2003. JR-Maglev is a broader system name, while N700S is a conventional wheeled Shinkansen train, not a maglev.