One year after becoming Diamond Friends, Aine and Mio prepare to enter the Star Harmony Academy High School. Aine and Mio begin a new journey in Aikatsu when they receive a distress call from a strange new idol, Hibiki Tenshou, from space.
Everyone is taken by surprise at Hibiki and her Jeweling Dress. In an effort to unlock the dress' secrets, Mio and the other girls ask Hibiki to show them Space Aikatsu.
Hibiki wants to get to know the idols of Star Harmony Academy so her producers create a TV show for her to interview them. However Hibiki decides to make things more interesting by changing the interviews to a prank show.
Mirai asks Aine if her protege Wakaba can shadow her for the day. Unfortunately Aine lets thing go to her head and nearly loses the chance of earning her own jeweling dress.
Hibiki is still no closer to reforming I Believe with Alicia and is at a loss at what to do next. Aine and Mio promise to inspire Hibiki to overcome her fear by overcoming their own fear of Love Me Tear.
After being asked by Hibiki to accompany her to the Sorbette Kingdom, Aine and Mio begin preparations to leave Japan. This proves more problematic than normal when Aine reveals she has never left Japan before, nor does she have a passport.
The girls finally arrive in the Sorbette Kingdom, but find they are banned from entering by the country's military on Alicia's orders. Aine and Mio decide to hold a concert to introduce the people of the Sorbette Kingdom to Aikatsu.
Despite Alicia's resistance to Aikatsu, Aine and the others still perform their Aikatsu while staying in the Kingdom. Alicia begins to question her feelings for Aikatsu when old memories begin to resurface.
Aine and Mio find out that they must return to Japan soon in order to continue their Brand Sponsorship. Hibiki believes that Alicia need only take to the stage and her love of Aikatsu will be rekindled.
Aine and Mio ask Hibiki when she and Alicia will start doing Aikatsu together as I Believe. Aine has an idea and tells Hibiki to ask Alicia on a Friends date.
Star Harmony Academy is holding an open day event for people to come and see the school and how the idols train. An old friend of hers appears at the school, causing her to become distressed.
Alicia receives some shocking news from her brother back home. Aine and Mio want to help, but must prove their ability to handle the workload by winning the Aikatsu Go Kart Grand Prix.
Alicia feels reluctant to reform I Believe with Hibiki, feeling she is far behind Hibiki in her Aikatsu having spent the past five years on hiatus. As Alicia struggles to catch up, Hibiki offers to assist her.
Kaguya has been offering advice to younger students, feeling it her duty to help nurture the next generation of idols, but feels conflicted when an opportunity arises that may end with her separated from her sister.
As the day of the Jeweling Festival draws closer, Aine and Mio begin to officially invite the participating idols. Aine and Mio begin to wonder Love Me Tear's year apart impact would Karen and Mirai's abilities on stage.
The Jeweling Festival is well underway with only Pure Palette left to perform. However the cold weather intensifies causing everyone to take shelter in doors. The idols band together to form a plan to continue the festival.