Shuchiin Academy is a beacon for talented students with a bright future ahead of them. The vice-president of Student Council, Kaguya Shinomiya, and the president, Miyuki Shirogane, are attracted to each other, but they are both too proud to be honest about their feelings, so all they do is think about how to get the other person to confess their love. Six months pass without anything happening between them, but then one day, the secretary, Chika Fujiwara, comes in with news about how she won a pair of free tickets to see a movie, a movie that supposedly turns males and females who see it together into romantic couples. This is the trigger that kicks off the romantic game of wits...

Kashiwagi's boyfriend goes back to Shirogane for more romantic advice while Kaguya eavesdrops again. Thanks to Shirogane's advice the first time around, the boy has been dating Kashiwagi, but a month has passed and the two haven't even held hands yet. To Kaguya, the question of what to do in order to hold hands is so simple that she's disgusted by it, but for Shirogane, who doesn't actually have any experience when it comes to romantic relationships, it's a relief since he feels capable of addressing the problem. However, like the previous occasion, Shirogane's advice seems to go in an unexpected direction...

After being forced to bail out on seeing fireworks with her fellow student council members, Kaguya shuts herself up in her dark bedroom. Hayasaka, Kaguya's maid, is worried about her mistress's depressive state. She tries to cheer Kaguya up, and when that doesn't work, introduces a plan to sneak out of the family mansion. Kaguya manages to slip past a pair of vigilant butlers and reaches the venue, but the fireworks display is already over. Kaguya is in tears, since she really wanted to see the fireworks with the others, but then she hears a familiar voice: "Then, I'll show them to you."

On their final day as the 67th Student Council at Shuchiin Academy, the four members clean out the Student Council Room where they find many memorable items, one after the other. From the banner used at the French exchange student welcome party, the deck of cards that was used to cheat during Concentration, the cards from the forbidden word game, the cosplay cat ears, the inappropriate magazine that was confiscated from a student, and the movie tickets for Mr. Birdson of Birdville, each of these items bring back fond memories and they can’t stop talking about their time together. And so, the four leave the empty Student Council Room behind...

The moment the culture festival reached its finale, the jewel object made by Shirogane was stolen by a phantom thief who calls himself Arsène. Kaguya and the others headed to the roof where the phantom thief keeps appearing, but there was no one there. Fujiwara, who transformed into a genius detective, struggles to solve the mystery behind the calling card and uncover the thief's true identity. But Kaguya, left behind at the scene of the crime, had begun to figure out the criminal. The problem is the location. Kaguya traced the phantom thief's line of thinking and headed to where he is now...

Shroud in a cape and dressed in the guise of the phantom thief Arsène, Shirogane waited for Kaguya's arrival atop the clock tower roof overlooking Shuchiin. When asked why he would do such a thing, Shirogane answered that there was something he wanted to show Kaguya. The festival's afterparty has already begun as the sun set over this school and the students could be seen encircling and enjoying the bonfire. While the emotions that could not be expressed with words mingled between Shirogane and Kaguya's hearts... Shirogane carried out his ultra-romantic operation!!