The Smart BEST is an experimental Japanese two-car self-charging battery electric multiple unit (BEMU) train developed and manufactured by Kinki Sharyo in 2012 to demonstrate the feasibility of battery train technology for use on non-electrified rural lines.

[1] The name is an acronym for "Battery Engine Synergy Train".

[1][2] The Smart BEST train operates using GS Yuasa LIM30H-8A lithium-ion storage battery modules[3] recharged in operation by a small-capacity "e-Brid Plus" diesel engine.

[4] The "Smart BEST" train was unveiled to the media in October 2012 at the Kinki Sharyo factory in Osaka,[4] before being moved to Yonago, Tottori for test running on the Sanin Main Line, Sakai Line, and Hakubi Line.

[2] From September until December 2014, the train was used in revenue service on promotional "Hello Kitty" services in the Wakayama area.