Unlike the first Idol Project, the story of the sequel is directly related to to the anime series Idol Project, starring the same characters, with the young and ambitious Mimu Emilton as the protagonist.

Mimu finds herself on a tropical island, where she must rise to fame by winning contests and promoting her singing skills. Like in the previous game, the majority of gameplay is dedicated to exploring the top-down city, visiting various places, searching for necessary people and raising the protagonist's parameters. Mimu has a much more detailed set of parameters than the hero of the previous game, including physical attributes as well as popularity rankings. The RPG element has been further enhanced by introducing random character (crazed fans and alike) who would sometimes attack Mimu on the city map and other locations.