Aine Yūki is a regular division student who's attending Star Harmony Academy. During the spring break preceding her second year in junior high school, she encounters the top idol: Mio Minato. With her great talent to make friends, Aine easily befriends Mio, having just one request to her: How about performing together on the Aikatsu! stage...?!

Aine's real Aikatsu! has just started. After transferring to the academy's idol division, she happens to belong to the same 'Production' as Mio. She's excited to get her very first job from her manager, Tamaki. On her workplace, the top idol unit that is ruling the Aikatsu! world, Love Me Tear's Karen Kamishiro and Mirai Asuka, appear!

Taking dress design up as well, Mio announces the reveal of her Premium Rare Dress in a week. However, she gets the feeling that 'there's something missing' and is unsure about approving the dress' design; meanwhile, Aine becomes Mio's 'one-day apprentice'. Will Mio be able to finish a Premium Rare Dress which will earn her approval?