The DEC700 is a low capacity diesel-electric multiple unit operated by JR West, being part of the efACE family.

[1] DEC in the name of the unit means Diesel-Electric Car, and is also matched with the correspondence to the positions of D, E and C on the Chromatic scale.

Based on JR West's vision of "creating a sustainable railway and transportation system", this railcar was built to assess in improving maintenance efficiency, safety, and reduce manufacturing costs through system integration of electric and diesel railcars, reduction of mechanical parts, and modular construction.

[2][3] The DEC700 was designed to be capable of switching to a hybrid system by using additional secondary batteries during technical verification.

[6] Separately, as part of efforts to achieve carbon neutrality, demonstration experiments were conducted between 2022 and 2024 to introduce "next-generation biodiesel fuel", expected to have the same quality as diesel with the experiments conducted using the model and the KiHa 40 series.