"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 suspected, to begin with. But seeing how busy the other Harunes are, Aira decides to help her family out. She goes to fetch an apron when Rizumu tells her to grab one for her too after she spots how worn down Aira's mom is by the counter. 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.
After they make a huge mess and ruin the supplies Aira and Rizumu apologize for what the naughty creatures did. Omi happens to come into the kitchen to do some cleaning, which causes Rizumu and Aira to feel worse since they had told her to relax. She insists that she doesn't mind though, and Neko-chi starts to mock them again. Stopping after Mion scolds her and walks out of the room. She takes out her phone and calls someone, explaining to them what has happened. As Aira and Rizumu join her she finishes the discussion and tells Aira that because they can no longer do anything at their shop with no more supplies and too much of a mess, they need to transfer shop.
This confuses Aira until the girls wind up at the front of Prism Stone, where Kyoko meets with them. She begins to speak as the Callings also come by. They are pretty excited about the girls working the Sweets Shop inside of the store the next day and promise to help out however they can. At first, Rizumu is annoyed, but she soon finds herself flustered and red hot as Hibiki teases her once again and walks off. The other two join him as Kyoko recalls something suddenly, and informs the girls they need to work on a duet the next day, so only today can they bake. Alarmed, Aira and Rizumu try to understand as Kyoko explains that it was a decided trade for letting the girls use Prism Stone for their replacement. She laughs before walking off, pleased with her work.
Inside, Aira is struggling to properly make the cream. Her brother and sisters are doing fine with their own work, but Rizumu is also shown struggling at the very end of the assembly line. She is scolded by the twins for backing their work up, and to her surprise, she suddenly spots 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 probably can't do it anyway. Mion puts together the perfect cake, but she is surprised when she finds Hiro there, instead of the others. Aira scolds her dad for treating Mion the way he is, but as he doesn't recognize who she actually is, he doesn't see anything wrong with it. Rizumu is stunned Mion has the talent to back her attitude, and Neko-chi explains that Mion is able to cook and bake very well since she is used to doing it with her parents gone so often, though Mion claims it to be nothing.
As the girls get back to work, Mion compares the baking to Batopon training, though they don't understand how. Aira struggles again with the cream until her father lends a hand. He shows Aira that the important thing to do is to relax and use the wrist, so the girls take this advice and they are able to make the cream.
Mion decides to take off while Hiro discusses how important timing is when it comes to cooking, and Rizumu recalls how Aira's brother watched everyone else while doing his own work so that he kept in pace with them. She decides to give this a try, then when she is able to put the cake together, the girls realize how important it is to focus on their partner instead of their own movements. They decide to give the Batopon a try once again and successfully perform the move, and in doing so they understand what Mion was saying. But as they need to hurry up and keep working they do not spend long celebrating the success.
The next day Mion walks by to spot everything they have made. Neko-chi is very impressed by this while she observes the customers throughout the shop before deeming it not to be so bad. Kyoko watches everything with glee, very glad to see how well the collaboration turned out.
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 and 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 the next Prism Jump, Wonder Sweets Show as the performance ends.
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, tons of new customers have just come in, and Rizumu quickly tries to get Mion to help out upon hearing this. She refuses to do anything, at least until Aira and Hiro desperately plead 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. She tries to think about it, but she and Rizumu find themselves distracted by the pancakes Omi brings in. 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.