A new school year begins with Yume now a fully-fledged S4 member alongside Ako, Mahiru, and Yuzu. As Yume launches her new brand, Berry Parfait, Ako is shocked to learn that the brand she was hoping to pair up with, Fuwafuwa Dream, has instead announced a contract with Kirara Hanazono, an idol from the ship-based idol school Venus Ark.

As the threat of Venus Ark looms over the school, Yume and Rola decide to put on a show for the first year students.

In trying to come up with a dress idea to rival Elza's Star Wings, Yume is told by her brand owner to think about what she herself would enjoy.

Wanting to take back Fuwafuwa Dream from Kirara, Ako sneaks into their headquarters with Yume and competes with Kirara to design the brand's new Premium Rare Dress.

Upon arriving at Venus Ark, Yume, Rola, and Mahiru are greeted by Koharu, who explains how she was scouted as a designer by Elza during her studies in Italy.

While doing modelling work, Mahiru hears about a mysterious model known as Shooting Star who vanished from the public eye one day.

Looking to relieve some boredom, Kirara decides to tag along with Yume and Rola as they do a report show on various spots around town.

Koukadou holds another audition for a new campaign unit, which Yume, Lily, Elza, and Kirara all receive invitations to.

As Yume struggles to come up with a Premium Rare Dress for her brand due to her busy schedule, Koharu decides to hold a fishing contest for a change of pace.

Yume and the others decide to do a feature on Elza for S4's show, during which they are escorted by a first-year student named Alice Caroll. Just as the feature gets underway, Elza suddenly tells Alice that she is to be expelled at the end of the day due to her declining popularity.

Ako is excited to be starring in a drama alongside Subaru, but struggles to keep her composure in front of him during a confession scene with him.

Tsubasa announces her plans to study abroad before informing Rola that she will inherit Spice Chord on the condition that she pass a series of tests.

As S4 are each given surprise one-day jobs for their program, Lily decides to becomes a guide for a fan tour to Suzukaze Plateau in leau of resting at her summer retreat.

With Tanabata approaching, Elza has Rei come out of retirement and resume model work as Shooting Star.

As Rola begins her duties as Spice Chord's muse and works on her own Premium Rare Dress, she and Yume are invited to be part of a Venus Wave event to increase their Aikatsu Ranking.

While preparing for her own performance, Yume comes across a young girl named Saya whose friends keep arguing over which idol is better.

Yuzu decides to hold a treasure hunt at the pool for her Shiny Smile brand's Premium Rare Dress premiere.

Venus Ark prepares to hold its proficiency tests, with Kirara sharing a rumor of a forbidden room on the ship where those who fail their tests are locked away.

While en route to preparations for the newest Aikatsu Island event, Yume, Rola, and Mahiru come across three idols from Starlight Academy; Akari Ozora, Sumire Hikami, and Hinaki Shinjō.

While kayaking in the sea, Yume, Rola, and Koharu get lost in a fog storm and end up on a remote island, where they come across Ichigo Hoshimiya.

Elza tells Koharu that the Venus Ark will be leaving Japan for a tour. Meanwhile, Yume, Rola, and Mahiru, whose exchange programmes aboard the Venus Ark are scheduled to end as a result, assume that they will end up having to part ways with Koharu once again, becoming worried when they can't find her aboard the ship before it departs.

Koharu wants to help Yume design some dresses for Berry Parfait, but can't find the confidence to ask her.

Noticing something off between Yume and Koharu, the other girls learn that they had gotten into an argument about Koharu's dress designs.

Yume and Koharu are scheduled to appear on a children's animal show hosted by Ako, where Kirara also brings her pet sheep, Caroline.

Learning that her parents are finally getting some time off work, Mahiru returns home with Yozora and Asahi to spend some quality family time together.