Airi and the Jewelpets have pizza for lunch while Sakutarō is away. However, he comes back on short notice and the girls quickly clean up everything. After getting back, he explained that the store he was visiting is closed on the holidays and never realized it. But then, he notices Kirara is hiding something, and eventually uncovers that she ordered pizza behind him by using a lie detector invention by him.
Fuming over her brother's gullibleness, Airi visits the Jewel Mall to blow off some steam. But then, Ruby notices someone out of the familiar: A pink dog, identified as King. The gang comes up to greet him, but then realize it's just an ordinary dog. However, Luna has her doubts about his typical appearance. As the girls pet 'King', a girl comes up to them. The girls see that she's the dog's owner, and that the dog's name is "Momohime". After they exchange pleasantries, she and the dog head off together.
However, Luna is still getting a hunch he is King. She noticed because his Jewel Watch is hidden inside of his crown. Surprised, the girl have decided to follow King. As they follow him, they start to have ideas why is he acting like an ordinary dog. Airi think he might have had a memory loss after coming from the Jewel Palace and probably realize he's a domestic dog. But Luna states that Jewelpets differ from human animals and Jewelpets are aware of species relationship. So the gang might realize King shouldn't act like a normal dog even losing his memories as a Jewelpet. Thinking it could be another mystery, Airi decides to call Sakutarō for assistance.
King's owner heads off to the bank while leaving him to stay outside. With her gone, Airi and the Jewelpets come closer to him to get a chance to speak with him. They want to "talk" to him by using Sakutarō's lie detector, to expose his identity as a Jewelpet. After answering questions, and despite him acting all adorable-like, the lie detector eventually reveals he's really a Jewelpet. But he still continues to act oblivious. Thinking it's still the memory loss, Airi asks Ruby to restore his memories. Though, she ends up making a heavy weight fall on King, but he manages to get out of the way.
King becomes exasperated to the horrors of Ruby's horrible magic. Realizes he is actually now speaking, his identity as a Jewelpet is exposed. So after they properly greet each other, the Jewelpets ask why is he pretending to be an ordinary dog. He explains that he has been the least popular Jewelpet in Jewel Land due to his failure in magic and skills. When the time came where he must leave the Jewel Palace to improve his magic, he only ends up living the life as a bad boy. Eventually, he was found by his owner to which he calls Sumire. Seeing how beautiful she trusts him, he decided to become her pet dog, and begs to the girls that he let him stay with Sumire. Feeling bad for his story, the girls have decided to allow him to like like a pet dog. Just then, King's owner Sumire comes out and comes across the girls.
The girls were eventually invited over to visit her apartment. They get to know each other chatting; Sumire being a University student. Airi then notices a photo of her and the pink Momohime. She explains that she and Momohime have been best of friends since childhood. But she was surprised that she (King) was in town and she was happy to have reunited with her. Luna secretly put Sakutarō's lie detector on her just to confirm it is true; to the girl's surprise. Sumire then heads out of the room to grab some tea. The girls tell to King that they will support his role being Sumire's dog.
Now looking after King, the girls have decided to give King some dog training at the detective agency. They give him dog performance training, though they throw in unrelated training like dances and household human chores. The second training they give him is veterinary inspection. Though the doctor's play ends up humiliatingly bad. Lastly, the girls take King to a dog park to give him dog communication training, though it didn't work out well. The sun sets, and King thanks the girls for the 'training' and that he understands how to act like a dog. So after he heads back to Sumire's room, he continues his dog impersonation with Sumire. She tells him that he is glad to have made some new friends. Airi and the girls leave knowing Sumire really loves King in his dog impersonation.
Just then, the two gets a visit from a door-to-door salesman and he offers to sell a golden good luck plate to her. But to King, he is under the premonition that the salesman is tricking Sumire into spending her earned money from her part-time job. He is considering of talking to her just to persuade her to not buy it, but then she will realize he is not to dog. As he tries to think hard, he realize he can call Airi and the others though his Jewel Watch. King calls them, asking them for help. So the girls rush back to the apartment to help King. While waiting, King notices Sumire is interested to buy the plate and comes back to the room. Quick thinking, King swipes Sumire's wallet and tries to keep it away from her. However, she distinctively orders him to give back the wallet and King had no choice but to comply. So as Sumire heads back to pay, King had decided to speak out to stop her from paying the salesman at the expense of his secret identity.
Then, Airi's pendant begins to glow and it transforms into magic power and travels a very long distance to King. He magically changes to take the appearance of a masculine adult man. There, he then stops the salesman from selling the plate to Sumire and takes it away to protect her. However, Sumire claims that she wanted to help men in their forties just to help them have a little good fortune, to King's confusion. She even believes that even after his human transformation she believes he is Momohime, but King still believes she might have not realized that truth. Airi and the girls arrive and try reasoning he is still a normal dog, even by speaking out with words at heart. Getting an idea from out her words, King begins to casts his magic spell on the salesman.
That following day, the girls say that the con saleman has disappeared and wondered what King's magic has done to him. It's revealed that he is now going door to door, apologizing to customers who've bought his golden plates. Airi then also noted that from her words, Sumire now accepts King, who is now in his open Jewelpet identity but still treats him as her trusty pet dog.
- This is the first full-length episode of the season.
- This is one of King's major invovlement in years since Jewelpet.