The 821 series (821系) is an AC electric multiple unit (EMU) train type operated by Kyushu Railway Company (JR Kyushu) in Japan since March 2019.

Two three-car trains were delivered in February 2018 for testing in preparation for full production and entry into revenue service.

[3][4] Details of the trains on order were officially announced by JR Kyushu in January 2018.

[2] Two three-car trains were delivered in February 2018 from the Hitachi factory in Kudamatsu, Yamaguchi.

[3] The trains first entered revenue service on 16 March 2019 on the Kagoshima Main Line.