Animated music video for Nijigasaki High School Idol Club's first song of their first single titled Muteki-kyuu*Believer sung by Kasumi Nakasu and Nijigasaki High School Idol Club's second song of their first single titled Mirai Harmony sung by the entire Nijigasaki High School Idol Club.
The BD release combines both with additional story bits that cover roughly 1 minute and 58 seconds into a single 8 minute and 30 seconds long animated video.
(Source: ANN, Anilist)