Action-ZERO is an insert song from Kamen Rider Den-O. It was performed by Yuto Sakurai & Deneb (Yuichi Nakamura & Hōchū Ōtsuka). This heavy metal song is the first ending theme that is not a "Double-Action" arrangement. However, it is still a duet between Yuto Sakurai and Deneb, and is used as the theme song for Kamen Rider Zeronos. A piano arrangement titled "Action-ZERO Piano form" was included as a B-side on the "Double-Action Wing form" single.