Yume Nijino aims to become a top idol, and she enrolls in the Yotsuboshi Gakuen (Four Stars Academy). This academy has a special group called the S4, who are the top four active idols in the school. Yume and the other first-year students aim to become a part of the S4.
Episodes
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.
The girls learn that Hime is passing on her My Little Heart brand to Aria Futaba, an idol who is popular in Finland.
As the Venus Ark returns to Japan, Aria searches around the ship with Yume and Kirara for some surprising Aikatsu.
Elza meets her mother, Yukie Grace Forte. Elza has aspired to be like her since her childhood: she was beautiful, shined as brightly as the sun, the world's top idol.
A Halloween night will be held at Four Star Academy, and the idols of Venus Ark will also participate, making it more hectic than usual. Yume and Koharu make a short plan in order to surprise everyone.
Rei makes a vow to obtain the last set of Star Wings, so that Elza's dream can come true. Putting her confidence and determination forward, she debuts her brand Royal Sword, gaining the final set of star wings, so that the Sun Dress can finally emerge; However, the Sun Dress appears randomly before one of the nine who have obtained star wings.
The students of Yottsuboshi Academy begin the shooting for the television program that they are appearing in. Under a time limit, it was supposed to be a show where one has to find a name card starting with letter "S". An intense punishment game called "Coochy-Coo" awaits those who fail to do so.
Yume is in good spirit to obtain the Sun Premium Dress. Appearing to be resuming her Aikatsu! activities immediately after resting, Yume pushes herself a bit too far and realizes that she no longer has an answer for what her favorite thing about Aikatsu! is. Among these events, she and Aria has been invited to co-star with Hime Shiratori on Hime's program.
Finally, the school festival has arrived to Four Star Academy, This year, the main focus of Four Star's school festival will be the play starring the members of S4. The chosen play is "Romeo and Juliet", rewritten for the students of Four Star. Venus Ark students Rei Kizaki and Kirara Hanazono appear in order to enjoy their time. Lillie also finds a prince.
In order to move up on the Aikatsu Ranking, Kirara has decided to enter the unit event that has extremely high points with Ako.
For the sake of moving up Aikatsu! Ranking, for all the upcoming stages, it will be extremely important to acquire the points from performances.
In order to move up the Aikatsu! Ranking Rola decides to enter a competition worth a lot of points so that she will have a chance of making the top four.
S4 receive a request to produce this years Christmas festival. Yume and the others come up with ideas for the festival, which include erecting a giant Christmas tree in the town shopping district and performing a show for the shoppers.
S4 realize they have a lot of work to do now that its new year but Yuzu decides to take it on all by herself. After taking on a full day of live program shoots, Yuzu succumbs to the strain and collapses.
Elza, Rei and Kirara talk about the past year and how everyone has grown from their experiences. Yume and Aria hold a concert before everyone gathers at Venus Arc to watch the new year fireworks.
Elza announces that she will be closing Venus Arc after the Aikastsu! Ranking final Tournament, leaving all the idols in distress.
Kirara suggests to Aria that she should enter an upcoming competition to raise her Aikatsu! Ranking, saying she needs to get serious if she wants to win.
The top four candidates for the Aikatsu! Ranking are announced. Yume and Mahiru from Four Star Academy, and Elza and Rei from Venus Arc.
Rei still tries to convince Elza to reconsider closing Venus Arc but to no avail. All the other idols aboard the Arc begin talking of leaving after the way Elza has treated them but Rei tries to convince them to stay.
Mahiru becomes hesitant about facing Elza in the tournament. Yume and the others manage to convince her that she has her own radiance that she can shine with.
Elza announces that she will quit being an idol once she wins the Aikatsu! Ranking Tournament. Rei decides she's had enough of Elza's selfishness. Unable to convince her to change her mind, Rei goes to Yume for help.
With the support of her friends, Yume prepares to take the stage, but before doing so she speaks to Elza. Elza is firm in her belief that a perfect idol can only shine alone, but Yume feels that an idol shines with the power of everyone who supports her and vows to prove it.
As Yume gets used to her new world wide fame, Elza is still adamant she will close Venus Ark. However the other idols refuse to leave and after some protesting, Elza realizes what she needs to do next.
As another school year draws to a close, everyone prepares for the upcoming S4 selection. However, Rola announces that she won't be participating this year as she is planning on moving to England to join a music producer called Black Star.
As the new school year begins, Rola prepares to leave Four star Academy for England. Koharu, Ako and Mahiru help Rola pack her belongings up when Yume shows up. As they discuss the future, both Yume an Rola feel they are forgetting something.
Yume, Rola, Koharu, Mahiru and Ako decide to spend their final vacation together having fun before Rola leaves for England. The girls spend a night in the country and are joined by Yuzu and Lillie.
