In 2032, the world was shocked when 7th Sisters, a legendary idol group, suddenly retired. The void left by their absence and the waning popularity of idols that ensued came to be known as the Idol Ice Age. After two years of these bleak conditions, 777☆SISTERS, a new idol group with 12 members partially managed by Coney Rokusaki, a 7th Sisters graduate, struggles to make its mark on the industry.

While they enjoy a degree of success, the group's impact is far less than the idols of yesteryear. When the girls learn that Hakkaku—the storied performance hall where 7th Sisters held many of their most memorable live events—is being targeted by a land developer for demolition, 777☆SISTERS take it upon themselves to perform there in hopes that they can demonstrate the venue's value. However, in a world where idols have fallen out of favor, it remains unclear whether the girls can capture the hearts of their audience.