The game centers on an event titled "Dream of Dream", set within a desolate old mansion named the "House of Seven Moons", where a central idol is set to be chosen from the members of popular idol group "Project 47". According to the game, "Project 47" is named after the 47 prefectures of Japan, and within the game's world is the largest and popular idol group in the country; the "Dream of Dream" is broadcast throughout Japan. The "Dream of Dream" event happens once a year, with the game's premise being the tenth reiteration. However, it is a lot different from usual, as lower-ranked idols are also included and no script was given; thus, the selection standards and how the winner is chosen remains unknown. Within "Project 47" are seven different teams, such as "Team Happy" (representing Kanto), "Team Smile" (representing Kansai), "Team Passion" (representing Kyushu) and "Team Rising" (representing both Hokkaido and Tohoku); amounting in total to over 200 contestants, sorted by rank. Central characters include:
- Mariko Kamata (voiced by Azumi Asakura), a veteran idol with 10 years of experience, having taken part in the first graduating class. She is a member of Team Happy.
- Chiharu Chigasaki (voiced by Emi Uema), an orthodox rookie idol who puts in great effort. She is a member of Team Happy.
- Shirase Tsubaka (voiced by Yurika Kubo), a young sister-type idol who adores Mariko and Chiharu. She is a member of Team Happy.
- Ayaka Tennouji (voiced by Yu Serizawa), an idol with a "strong sense of justice". She is the leader of Team Smile.
- Rito Karasuma (voiced by Asuka Nishi), a talented idol who adores Ayaka. She is a member of Team Smile.
- Ren Isahaya (voiced by Mao Ichimichi), a beautiful girl with an androgynous appearance. She is a member of Team Passion and has won the last three consecutive "Dream of Dream", but always boycotts her centre inauguration.
- Doripaku (voiced by Kappei Yamaguchi), a pink-costumed character with an appearance of a tapir whom controls the "Dream of Dream" as the program's host. He is a "mysterious" character who claims he came "to make the world much more interesting", and enjoys "manipulating people's emotions and lives".