Bermuda △ Triangle: Karen on Stage ♪

Bermuda △ Triangle: Karen on Stage ♪ is a volume derived from the wider Bermuda Triangle multimedia project, which was developed by Bushiroad as a spin-off of the Cardfight!! Vanguard franchise. The series focuses on the idol group known as the Bermuda Triangle, primarily featuring mermaid characters in an underwater setting, blending slice-of-life storytelling with the thematic elements of idol performance culture. It was produced to expand the lore and character depth of the card game's units beyond their standard competitive applications.

The illustrations for this volume were provided by Ishida Aya, who worked to capture the vibrant, energetic aesthetic typical of the idol subgenre. The design philosophy centered on high-detail character portraits and expressive, dynamic paneling that highlights the stage performances central to the narrative. Upon its release, the volume was received primarily by the established fan base of the card game and the surrounding multimedia project, serving as a supplementary piece for those invested in the franchise's character world-building.