What is "defspiral"

Defspiral (stylized as defspiral, and briefly existing under the name Wilma-Sidr) is a Japanese visual kei rock band composed of most of the former members of the Underneath. When the Underneath disbanded in 2010, most of the group was signed to Avex Mode to perform songs for the Kamen Rider Series. This occurred with a change to their style to a smoother, slicker and more seductive style than their previous incarnations.