During the spring break preceding her second year in junior high school, a regular division student named Aine Yūki 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.

Upon transferring to the academy's idol division, Aine happens to belong to the same 'Production' as Mio, being excited to get her very first job from her manager, Tamaki. On her place of work, 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 is something missing and is not sure about approving the dress' design. Meanwhile, Aine becomes Mio's "one-day apprentice".

With the advice given to her by her production company's stylist, Chiharu, the still idol-egg Aine begins her search for a brand that fits her. Although so many brands are around, it seems neither works.

Wanting people to discover the brand only for her, Sugar Melody, Aine thoughtlessly enters an audition to be the MC in Love Me Tear's event. On the venue, she meets Maika Chōno, an idol who loves festivals.

A senior student named Ema Hinata showed off her leadership skills even at a camp that she went to. However, Mio is not fitting in well with this environment, causing a chain on confusions.

Upon being selected by Love Me Tear's Mirai for a guest role in the drama "That Idol's a Witch!", Aine is supposed to memorize her lines and practice well. However, Aine keeps making mistakes, so seeing her in such a situation, Mirai decides to take her out for some time.

A famous world-class creator is to be chosen as a director for a commercial for macarons, with Mio going to be filming the commercial when they are faced with a surprise. However, the background music is an Ondo, and is not fit for a macaron commercial. It is up to Mio to make an impactful "Big Bang" CM when nothing goes as she had predicted.

Upon asking Coco from Aikatsu Navi and learning that if she is an "amazing idol", Aine obtains a premium rare dress. In order to let herself be more well known among the fans, Aine begins to plot a fan meeting of her own.

Ema and Maika are searching for a Friends partner. From an outside perspective, the two fit each other perfectly, going against their expectations. Although their personalities and preferences are polar opposites, no matter how the two look at it, they have the best compatibility.

Mio finally begins to take action in order to form a Friends unit with Aine. She aspires for a dramatic situation like with Love Me Tear's legendary formation story. While seeking the perfect timing to speak with Aine, for some reason, Aine seems to be intimate with Nako Ebihara, an idol from Nagoya.

Mio wants to go to school with Aine everyday, but is unable to say it. At this time, a large amount of tomatoes are delivered to the Penguin Cafe. Having been present, Mio is roped into helping out with a cafe event as the Yūki family's event is almost closed.

In order to get Pure Palette's name more well-known, Aine and Mio are to appear on the TV program "Genius Battle Selection". However, Karen Kamishiro reigns as the absolute queen of geniuses on the show. Admiring and aiming to surpass them, Mio comes to face Love Me Tear, and learns the essentials of Aikatsu! from Karen.

Ema is asked to design Honey Cat's Best Friends Rare Dresses. While attempting to bring together both their dress designs, as Ema and Maika's tastes are polar opposites in the first place, they cannot come up with a design that makes use of each other's personalities.

After four months have passed since Aine has begun her Aikatsu!, she even uploads "tried to do" videos onto AiTube under Mio's instruction, but the number of views do not increase much. Mio, assessing the situation, seems to become aware of Aine's greatest talent.

Mio starts getting pumped up for she is trying to design a Best Friends Rare dress for Pure Palette. When Mio reaches a wall in designing, Aine invites Mio on a mystery tour planned by Aine herself. Walking along the lands of the forest, they reach the place known as "Hero's Bridge".

A young fortune-teller named Sakuya Shirayuri pays a visit to Penguin Café, and gives Aine and Mio a reading in regards to their upcoming audition. Understanding the meaning behind the reading, the two have a task to create a big bang.

As the school's event, the Star Harmony Cup, is about to begin, Honey Cat is having a training camp in the gym so they can pull off a Friends Appeal worthy of their dresses. The two undergo lessons while also busy with work.

In order for Pure Palette to win the Star Harmony Cup, Aine aims to raise her abilities. Unusually separating herself from her friends and family, Aine trains extra hard by herself. As a result, though her dancing and singing have improved, she is missing something important.

Ema and Maika regret losing to Pure Palette. Feeling that their defeat was a result of being unable to face their fans, they plan out a fan meeting tour. However, the day of the event overlaps with Ema's lacrosse club's training camp.

Aine and the others volunteer to be visitor guides at the academy's open day. Joined by powerful visitors from all countries, they observe the ongoing events of the school. Hearing participants who say that there is no need for Friends, Aine enters a situation where her friendship power is ineffective.

In order to protect Sakuya's reputation as a fortune-teller, her sister Kaguya fills in for her while she does her Aikatsu!

Still upset over losing to Pure Palette, Maika has yet to tell her parents she will not be competing in the Brilliant Friends Cup. As Maika struggles to hide the truth, it begins to affect her work. The designer of Dancing Mirage, Maika's favorite brand, tells her she isn't ready to become the brand's muse. Feeling lost about what to do, Ema steps in to help.

Pure Palette and Reflect Moon are planned to appear on a variety show with Love Me Tear. Although Sakura is nervous about her first variety show appearance and Kaguya is unable to understand something amazing about Love Me Tear, the two go to the recording.

Mio is asked to cover for Love Me Tear on a variety show when the Friends get stuck abroad. However,Mio is initially reluctant to accept the offer as she still feels she is far from surpassing Love Me Tear. Mio prepares thoroughly for the show and things go well, but when a surprise guest appears, she needs to pull all her skills and resources to perform successfully.