At first, Ryouya figured the study tour would just be a repeat of his bad middle school experience. But with Reona and Riona around, he actually ends up enjoying the trip to Kyoto and starts realizing he doesn't want to lose them. Behind all the attention and teasing from the twins, the two of them are deliberately making Ryouya more and more dependent on them, including by monitoring his phone and stirring up his jealousy. Ryouya still doesn't fully get how serious their feelings are, while Reona and Riona have already planned to make him officially their boyfriend at the school festival.
Characters:
MC: Yagami Ryouya
Heroine 1: Tsurugi Reona
Heroine 2: Tsurugi Riona
MC's sister: Yagami Mio
Summer break's over, and Ryouya's back at school. He's not exactly thrilled since the study tour and school festival are coming up soon. Back in middle school, his group left him behind and he ended up spending free time all alone. Because of that, the study tour reminds him more of a bad memory than a fun vacation.
Before leaving, Ryouya tries not to wear the two matching rings he's been required to wear since Reona and Riona's birthday. But the twins immediately notice and ask about the rings. He ends up putting them on, one on each ring finger, left and right. They also warn him there'll be punishment if he forgets again.
On the way to school, Ryouya gets some shocking news. Reona and Riona already switched their study tour destination from Hokkaido to Kyoto just so they could be in the same group as him. They don't want to let him go anywhere unsupervised. Ryouya feels like he's being treated like a little kid, but he's also relieved that this time, someone will actually be with him.
In class, his classmates are still keeping their distance after the wallet-missing incident before break, back when Reona pressured them not to just randomly accuse Ryouya. He doesn't really mind it that much. At least nobody's asking about the rings on both his hands.
Ryouya then falls asleep at his desk and almost misses the opening ceremony. Reona wakes him up by tickling him, then tells him he owes her a favor now. Ryouya just hopes whatever she asks for later isn't too much of a hassle.
After school, Ryouya and Riona want to head straight home since they're tired, while Reona still wants to hang out. Reona eventually gives in, but it turns out she actually plans to go to Ryouya's house instead of her own. Riona immediately falls asleep on his bed, while Reona helps Ryouya with his homework.
Ryouya's surprised at how skilled Reona actually is. He always assumed Riona was better at handling the house, but turns out most of their packed lunches are actually made by Reona too. When Ryouya compliments her looks, skills, and kindness, Reona gets flustered. She teases Ryouya all the time, but a direct compliment from him still makes her shy.
Mio then comes home with groceries and realizes she forgot to buy eggs for making omurice. Ryouya offers to go to the supermarket, and Reona tags along. There, they run into Sayaka Matsuyama, Ryouya's childhood friend and first love. Those feelings were never actually confessed back then and ended once Sayaka got a boyfriend.
The moment Reona finds out who Sayaka is, she immediately goes on alert. She links arms with Ryouya and claims to be his girlfriend. Ryouya tries to deny it, but Reona shows off their rings and even brings up that they've bathed and slept together before. Even though the whole "dating" claim isn't actually true, Ryouya still has a hard time explaining it away.
Sayaka actually thinks they make a good pair. She's never seen Ryouya talk so casually with someone before. After Sayaka leaves, Ryouya realizes he forgot to ask her not to spread the news. Reona herself admits she briefly saw Sayaka as a rival, but felt relieved once she figured out Sayaka wasn't actually interested in Ryouya.
At home, Reona cooks omurice with Ryouya's help. When Ryouya says he thinks she'd make a good wife, Reona immediately teases him like he'd just proposed to her.
Once the food's ready, Ryouya has trouble waking Riona up. Reona tries to make him kiss her little sister, then pushes him so he falls on top of Riona. Riona wakes up right at that exact moment. The two of them then tease Ryouya like he was deliberately trying something. At dinner, Mio joins in on the teasing too, making Ryouya's explanation basically go unheard.
A few days later, the school holds a study tour briefing. While Reona and Riona are talking with their friends, Ryouya waits around playing a game. He manages to get a rare character, but Riona grabs his phone and transfers the character to her own account. According to the twins, that's punishment for choosing to play games instead of paying attention to them.
Reona and Riona have also already told their friends they'll be in the same group as Ryouya. That way, he won't have to worry about getting left alone like in middle school. But a few other students look unhappy that the twins chose him over them.
While discussing places they want to visit, Riona suggests a shrine famous for cutting off bad relationships. Ryouya's confused since he barely has any friends to begin with. The twins explain they want to keep unwanted people from getting close to him.
On the way home, they get caught in heavy rain and duck into a bathhouse to wait it out. They bathe separately, but once they're out, the twins start teasing Ryouya for not even trying to peek.
In the lounge area, they offer him a massage. But the massage turns into touching and teasing Ryouya didn't ask for. He asks them to stop, but they both keep going until they're satisfied. Ryouya heads home feeling even more exhausted, both physically and mentally, than before.
The next morning, while Reona and Riona are still asleep in his bed, Ryouya wants to go buy a card for his game. He sneaks out quietly so he won't wake them up, but forgets to bring his phone.
When he gets back, the twins are already waiting at the door. They accuse him of possibly secretly meeting another girl. The receipt isn't enough to convince them. Both of them demand a body check and pressure Ryouya into taking off his clothes. Once they're satisfied with the inspection, they say he's forgiven for that accusation. But since Ryouya also forgot to wear his rings, there's still another punishment yet to be decided.
They then go eat at a sushi restaurant. There, Ryouya runs into Kaisei Shimizu, a middle school classmate who used to tease him a lot. Kaisei had heard Ryouya has a girlfriend but didn't believe it. After seeing Reona and Riona, he suddenly claims to be Ryouya's best friend.
The twins immediately fire back. They claim to be Ryouya's girlfriends, then criticize Kaisei's lies, his fashion sense, and his behavior until he leaves out of embarrassment. Ryouya feels like they went a bit too hard, but he's still grateful the whole disturbance is over.
While eating, he even offers to feed Reona. Riona immediately demands the same thing. To them, whatever's given to one sister has to be given to the other too.
As the study tour approaches, the three of them go shopping for travel supplies. While Reona and Riona are in another part of the store, a female employee shows Ryouya how to use hair wax and helps style his hair. Ryouya likes the result, but the twins find a strand of a woman's hair on his shoulder and notice a different scent.
They're not okay with another woman touching his hair. To undo the styling the employee did, they decide to dress Ryouya up as a girl. This also doubles as punishment for his previous mistakes.
Ryouya gets dragged along to pick out a wig, try on women's clothes, and get made up. Once it's done, the two of them start calling him "Ryōka" and keep dragging him around the mall. He wants to change back right away, but they're not ready to stop yet.
When he's finally allowed to change back into his own clothes, Ryouya has to wait for an empty restroom. Two guys then approach him, mistaking him for a girl. Ryouya chooses to stay quiet so his voice won't blow his cover, but they keep pushing him to come with them.
Reona and Riona show up and claim to be his girlfriends. Since the two guys don't believe them, Riona suddenly kisses Ryouya to prove it. The guys finally give up and leave.
After Ryouya changes back into his own clothes, Riona tells him that was her first kiss and asks what he thought of it. Ryouya realizes he's now been the first kiss for both sisters, even though their relationship still isn't officially boyfriend-girlfriend.
That night, the twins' conversation reveals they really do want to have Ryouya for themselves. Some of the earlier problems were deliberately set up by them, though a few things also happened without being planned. They feel like all of it still helps Ryouya get more and more used to being around them. Reona also still doesn't like the employee who styled his hair and won't let her get close to him again.
On departure day, the twins style Ryouya's hair themselves. On the train, he sits between them. When they board the bus, Reona and Riona have already talked to their friends so the three of them can sit together in the back row.
Throughout the trip, they keep asking Ryouya about the type of girl he likes. If his answer doesn't match their looks or personality, they immediately push back. When Ryouya picks a petite girl since he feels like he's not tall enough, they explain that height doesn't matter if someone truly likes him.
At Kiyomizudera, Reona goes to the restroom but doesn't come back by the time it's Ryouya and Riona's turn to get water from the Otowa waterfall. Reona left her phone in her bag, so they can't reach her. After waiting longer, the two of them split up to look for her.
Ryouya finds Reona with three big foreign tourists. He assumes she's being bothered and immediately steps in. Turns out, Reona's just helping them find the way to Fushimi Inari. Since she didn't have her phone, she had to ask someone else for directions first.
Ryouya feels embarrassed for misunderstanding, but Reona's happy he came to help her. Still, she warns him not to do that kind of thing for other girls. According to her, only the two of them deserve that treatment. Riona then buys Otowa water so Reona can still have some, even though she missed getting it herself.
At Arashiyama, Ryouya catches Riona as she almost falls after getting pushed by other visitors. The twins then both hold onto his arms, saying it's so she won't fall again. While eating ice cream, Riona also kisses his cheek to wipe off some cream that got on it.
As they walk through the bamboo forest, Reona gets a message and goes to meet someone. Riona secretly drags Ryouya along to follow her. They see a popular basketball player confessing his feelings to Reona.
Ryouya thinks the guy's a much better match for her. But Reona immediately turns him down. Ryouya feels relieved, but also starts realizing he doesn't want to see Reona end up dating someone else.
That night, at the hotel bath, Ryouya overhears other students complaining that he's always with the twins and that it makes them hard to approach. That conversation makes his insecurity even worse. He feels like maybe he's getting in the way of Reona and Riona finding better partners.
Ryouya then leaves the hotel without telling anyone and sits alone by the Kamo River. Reona and Riona find him there. Instead of scolding him right away, they ask what's on his mind.
Ryouya explains he feels like he doesn't measure up to them. The twins reject that reasoning outright. If some opportunity ever required them to leave Ryouya behind, they wouldn't want it. They also forbid him from pulling away "for their own good." Ryouya feels calmer after that, and the three of them head back before the attendance check.
After they part ways, the twins' conversation reveals something Ryouya doesn't know about. They found him through a GPS app secretly installed on his phone. Riona also already knew Reona was about to receive a confession and deliberately brought Ryouya along to witness it.
The goal was to make Ryouya scared of losing them. Both of them also admit they'd arranged things so other students would like him even less, even though they don't know exactly what conversation he overheard that night. They want Ryouya to find it harder and harder to pull away, and they're planning to lock down their relationship at the school festival.
On the second day, the three of them visit a shrine. Ryouya writes a wish to get rid of his habit of negative thinking. Reona, on the other hand, wishes to cut Ryouya off from anyone who might get in the way of their plans. Riona writes that anyone she considers unworthy of Ryouya should be kept away, including people from his past or anyone who might show up in the future.
After that, they head to an aquarium. Riona really enjoys watching the giant salamanders and garden eels. The three of them also happen to witness an argument involving a guy named Ryouya and two women who both claim to be his girlfriend.
Reona and Riona use that moment to bring up cheating. They make clear that no other girl's allowed into their relationship. When Ryouya asks why sharing a partner between the two sisters is allowed, the answer stays the same, they consider themselves one unit since they're identical twins.
Their next stop is a theme park based on Edo-period films. Ryouya rents a Hijikata Toshizō costume, Riona picks a kunoichi outfit, and Reona goes as a maiko. They take photos together. Ryouya also finds out his mom's been following Reona's social media account and has seen their photos.