Mikage and Sudachi are looking through a magazine while at the candy shop, and discover a new and adorable hoodie. Mikage wishes that she had the money to afford it, which prompts the store owner tells her to not say things like a ‘lousy adult’. Sudachi is also short on cash, and inadvertently reminds Mikage that Valentine’s Day is coming up. Mikage says she would love to buy a large chocolate cake if she could, but she had just spent the last of her allowance on a popsicle. As she mopes over this, Sudachi tells her about something she saw on the internet called ‘The Straw Millionare’. It was about a guy that started bartending with a simple paper clip, but in the end, he got himself a house. Mikage checks her popsicle stick, and notices that it was a winner, and can be exchanged for a prize. Encouraged, she decides to try the challenge, and makes her first trade with Sudachi, receiving her ramune for the popsicle stick. Soon after, Jun makes a surprise visit to the shop after she left Kamihama for two years. After a warm reunion, Jun meets the two girls and decides to join in on their straw game. Mikage offered her ramune to Jun after she had planned to get some herself, and the second trade was made. Jun bought a large bagful of candy, with the request that the two friends kept coming back to the candy shop, vaguely alluding to her wish.
That evening, Mikage gets home with the bag of candy, and overhears Mitama getting upset over not being able to afford a high-brand hair mist that she wanted. She comes out of her room and gets embarrassed that her sister heard her, knowing that she needs to be a good role model. Mitama offers to make dinner for Mikage, before noticing the bag of candy. Mikage briefly gets anxious, before explaining ‘The Straw Millionare’ to her. Mitama curiously asks about what her goal target is, and Mikage pauses, before saying that she wanted to get a nice Valentine’s Day gift. Happy for her sister, Mitama wishes her luck.
The next day, Mikage visits Nayuta and Lavi, and tells them about her plan while offering the bag of candy. Lavi agrees as long as the trade is fair, even by a little. She offers a storybook titled ‘By Otranto’s Seashore’, which was based on a folktale. Lavi had accidentally purchased two copies of the book, excited by the fact that Nayuta’s father had helped translate it. She also claims that since the copy was brand new, it would sell for a good price at a secondhand book store, so Mikage decides that her next stop is Kako’s bookstore.
However, when she arrives and begins talking with Kako, she notices a sign saying that items will not be bought from minors that don’t have a guardian present. Disheartened, Mikage exits the store with an apology, leaving Kako confused. When outside, Mikage wonders about what she should do, but the moment is short lived when Kush, who was sleepwalking, bumped into her, causing both of them to fall over. Kush apologizes and tries to deny that she was sleepwalking, only to. Briefly fall asleep on the spot. Mikage’s bag had spilled out when she fell, exposing the book and Kush recognizing it as a book that she was looking for. After the two introduce each other and discuss the straw game, Kush offers to trade some mall gift certificates, while expressing her admiration for the book’s author. She then stumbled off to her night school, barely awake once again. Mikage was confused and worried about her lethargic demeanor, but was excited that she would be going to the mall tomorrow.
The following day, Mikage looks around the mall and begins browsing the cakes being offered. She briefly gets tempted to proceed with her initial Valentine’s plan, before recalling how Kush sounded when she received the book she wanted, and decides to move on. Mikage then finds a game corner, and remembers overhearing the conversation with Jun and then candy shop owner, where the former mentioned wanting a certain large star squid plush. In one of the crane machines, Mikage finds that exact plush. With many tries, and using up all her certificates, she finally manages to win the plush.
That night at home, Mikage hops onto an online exchange bulletin board, and finds a request for the squid doll, and one of the items it was offering to trade with, was the hoodie that Mikage wanted from the magazine. She contacts the person behind the post, and is surprised by how quickly they responded. The trade goes off without a hitch, with the user saying that the squid doll was intended to be a present, most likely to Jun herself. The two package their items and mail them, with the poster covering the shipping costs. A few days later, the hoodie arrives in brand new condition. Mikage decides to try it on just once, and ends up loving it to the point where she wails about wanting to keep it. Overhearing her outburst, Mitama asks about how the challenge is going, and Mikage confesses that even though she got what she initially wanted, she was tempted to stop and just keep the hoodie. Mitama sympathizes with her, stating that they’re sisters, and that it is important to acknowledge said feelings, but then decide on what to do next. Mikage thanks her sister for the advice, and to go trade the hoodie for something even bigger, where everyone can be happy. This whole time, Mitama thought this was all for Sudachi, but was promptly told that the two friends each have someone important in mind, leaving Mitama to wonder about who it could be.
A few days later, Mikage brings her mother to the flea market so that she could actually participate, and at the end of the day, she was finally satisfied. On Valentine’s Day, Mikage surprises Mitama with the gift that she had been building up to. Upon opening it, Mitama discovers the Roné hair mist that she really wanted. Realizing everything, Mitama tearfully thanks her sister, before asking how she went from the hoodie to the hair mist. Mikage explains that since the hoodie was brand new, lots of people wanted it, and she got a high-brand fragrance that she later traded for the hair mist with Nayuta, who used it all the time. Mitama hugs her, saying that she’s grateful and proud to have a sister like Mikage.
Some time later, Mikage is back at the candy shop, however, she is now wearing the hoodie that she wanted. She tells Sudachi that Mitama bought the hoodie for her as a way of thanks. The candy owner is impressed that Mikage didn’t waver from her objective during the whole thing, but Mikage calls herself a bad kid for having thoughts of temptations. The candy woman tells her that since she was able to overcome those temptations, two sisters and their smiles were able to blossom. Mikage finds herself agreeing as Sudachi smiles along with her.
