"A Happy Lucky Summer is a Cake Crash Course!" is the seventeenth episode of Pretty Rhythm Aurora Dream.
Rizumu and Mion help Aira and the rest of the Harune Family during their busy summer schedule at the Shop.
As Rizumu and the clumsy Aira Batopon train, they find themselves distracted with thoughts regarding their summer plans. They have a lot of time left to practice and would rather discuss the sales, pool visits, festivals, and so on. Aira asks Rizumu to come over to her place so that they can make plans together.
The girls arrive to find the Harune Household crowded with customers. Aira runs back to find her dad busily working as he explains the recent recommendation the shop received from a popular male idol group the day before. He shows them the magazine article, and the girls are quickly able to confirm it was who they assumed it to be. But seeing how busy the other Harunes are, Aira decides to help her family out and runs off to grab an apron. Rizumu offers to help after noticing how tired Omi, Aira's mother looks. When Aira returns she tells her Mother to take a break and they get right to work.
At Pretty Top, Mion continues to reject job offers from the frustrated Kyoko. Kyoko is frustrated and tells her that she shouldn't be so picky, but Mion claims she hasn't had anything worth looking forward to lately. Nothing motivates her anymore, and to prove her point that she already knows what will happen, she tosses her Batopon into the air and catches it behind her back. Jun questions if she may be tired of Prism Shows and compares Mion to a sleeping Lion, saying that even the most talented of hunter will give their all when pursuing their prey. She claims that her situation is different and takes off, heading over to the Harune Cake Shop.
There she finds the girls and asks why they aren't training. Aira explains what happened and Mion walks into the kitchen to find Hiro. Neko-chi criticizes the size of the small kitchen and this agitates Rizumu, so she demands that Mion lend them a hand. Mion doesn't see a point though, and to settle them down Aira offers her a little cake. Neko-chi is quick to quip that Mion would never settle for something so simple and little, considering she could get one worth more value from a fancy restaurant with many stars if requested. This angers Rabi-chi and Bea-chi though, and they start to chase after her when she starts to mock them.
The resulting argument makes a large mess of the kitchen and ruins several supplies, causing the girls to feel remorseful after Omi comes inside to clean up. She claims not to mind when they try to apologize, and Neko-chi resumes mocking them. Mion scolds her and leaves the room, then she calls for someone for help before informing Aira that the best idea right now would be to transfer shop temporarily as they don't have anymore supplies and there's too much of a mess. Aira is confused until she brings them to Prism Stone, where Kyoko awaits to chat with them. They are joiend by Callings, who promise to lend them a hand the next day when needed. At first, Rizumu is annoyed, but she soon finds herself flustered and red hot as Hibiki teases her before they take off.
Suddenly Kyoko recalls something and brings up that the girls must work on a duet the next day, so only for today they can focus on baking. This alarms the girls and she explains that Mion made it their trade for letting them use Prism Stone for their replacement, and she laughs before leaving them.
With nothing left to lose the girls head inside with their family to get started. Aira struggles to make cream while Rizumu has issues at the end of their assembly line, which they work with Aira's siblings. Eru and Uru scold Rizumu for backing them up, and to everyone's surprise they spot Mion. They assume she has come to help, but she refuses until Rizumu is able to bait her into it by mocking her; claiming that for someone so high and mighty she's probably trying to avoid saying she can't do it. But after Mion assembles the perfect cake in seconds she appears stunned as Aira scolds her father for treating Mion the way he does. Neko-chi goes on to explain that with her parents gone so often, Mion learned how to bake and cook. She remains modest and insists it's nothing as they resume working, and she begins to compare it to Batopon training.
With Aira and Rizumu unable to undersand how though, they continue to struggle. It's then Hiro joins Aira to lend a hand and explain that relaxing and using the wrist will help make the cream the desired texture they need. He hen goes on to explain how important timing is when it comes to cooking and Mion decides to take off. Rizumu realizes that Aira's brother, Itsuki was watching everyone else as he did his own work so that he was able to keep pace with them, and she uses this to try to assemble a cake.
This makes the girls realize how important it is to focus on their partner rather than entirely focusing on themselves, and inspired they decide to do some Batopon training when given a chance. They are able to successfully perform the move and happily remark on how they understand what Mion was trying to say- but with so much left to do their are given little time to celebrate and get back to work.
The next day Mion walks by to spot everything they have made. Neko-chi is very impressed as she observes the customers throughout the shop. As this is going on Kyoko watches with glee over how well the collab went.
Aira and Rizumu head out onto the ice with the intention of performing the double move they have been working on. They begin to dance and jump into the air to perform the Colorful Chocolate Parade Duet, and while they perform Mion comes to watch when she spots Kyoko. The girls think about what they learned earlier and together connect their Batopon and toss them into the air to catch each others' before performing 'Wonder Sweets Show.
At the shop, Aira's little sisters compliment the wonderful show when Mion approaches. She manages to tick off Rizumu, but Aira thanks her for her help as her brother reminds them that they shouldn't celebrate their success yet since they need to keep working. Hiro then comes in to reveal that due to the successful show they got tons of new customers, and hearing this Rizumu quickly attempts to get Mion to stay and help them again. She refuses until Aira and her father desparately begin to beg her.
That evening at the Harune House, the girls are resting after their long day. Mion awakens to find Aira and Rizumu still passed out and decides to take off. But she is surprised when Omi comes into the room and offers her some pancakes as a way of saying thank you. Neko-chi assumes Mion wouldn't want them, but as Mion begins to eat, Aira and Rizumu wake up. Omi heads back into the kitchen to prepare more after Mion finishes hers and goes to leave. Aira tries to get her to stay, but she refuses and takes off. Rizumu criticizes Mion by saying she could be friendlier to them, but Aira just notes how Mion seems to be a little different now as her mother brings in some pancakes. After sharing a laugh the girls begin to dig in.
Prism Stone Shop
Jubi decides to teach the girls a new technique known as the Batopon Spin. She shows them how to do it, then has them keep adding a spin onto each turn so that they get used to it. She decides to combine everything they've learned so far and they start to dance to the music, ending it after they reach the Batopon Spin portion. With that she has them review the move while Rabi-chi, Bea-chi, and Neko-chi begin the episode.
The girls decide to study the Popping dance style. They comment on that it is important to perform a move that people normally do not force their bodies to do, so they tell them to make sure it's properly stretched first so that it can get used to the moves. They do a little dance, then Rabi-chi, Bea-chi, and Neko-chi see how far their ranking has improved. The girls give their usual farewell comments and end the episode.