Rina is searching for the oranges she dropped below the table when Kazuya comes and calls her. She trying to stand up by instinct and bump her head. Kazuya gives Rina her orange he found outside the home economy room, he says it reminds him of the first time she met Rina when she dropped her oranges. After that Kazuya says he's ready to take picture of Rina's homemade cooking like he promised before, helping her putting pictures on academy's website to attract people to join her cooking club. Kazuya then begins to take picture of the cooking process.
After the marmalade scone Rina made has finished, Kazuya sets up for the photo session process, Rina says that Kazuya looks like a pro cameraman already. After the photo session finished, Rina offers Kazuya her scone and feed him. Some of marmalade is left off on Kazuya's cheek and Rina takes it off and eat it, she then realizes she has done something embarrassing.
"Ah... I-I'm sorry! I-it's like what usually happened with my little sister, so I..."
"D-don't worry, it's okay it's okay..."
"B-but... Compared to when I tasted it when I cooked it, it tastes sweeter and more delicious.... E-eh, what did I just say. P-please forget it!"
"I-I wonder if I could forget that..."
Days later, Rina informs Kazuya that his pictures are already approved and uploaded to the academy's website by stuco prez Aki, since Rina can't use PC too well. Rina then says she wants to do something for Kazuya as her token of gratitude for helping her, but Kazuya says he already ate her scone so it's not like she owns him anything. Rina insists, so Kazuya says if it's okay with her, he wants to go somewhere again with her alone, like when they played to Dart Cafe days ago. Rina agrees and she suggests to go to theme park since she has pair ticket so they decide to go there on the weekend.
Kazuya goes to his clubroom while grinning like crazy because he will go on a date with Rina, it makes his clubmates wonder what happen to her and ask if he's succeed taking some erotic picture of Rina. Kazuya then tries to cleaning the room and sorting all the boxes when he accidentally fall and the content of the box is revealed, which is a cosplay suit he remembered from the magazine Uchida read days ago. He also notices that Uchida and the cosplayer wearing the suit has the same mole under their right eyes, it makes Kazuya wonder if Uchida and the cosplayer girl is the same person.
Weekend, the day of Kazuya and Rina date, Kazuya is waiting for Rina in front of the station when a little girl is poking his arm. The girl sounds like she knows Kazuya, asking him to go to the theme park already and the first thing pops up on Kazuya's mind is Rina magically becomes a little girl
Short moment later, Rina comes and turns out the little girl is Rina's little sister, Erina, 2nd grade elementary student. Rina tells Kazuya that Erina insists to come with her big sister after Rina told her she will go to the theme park. Kazuya says it's okay with him because he understands what it feels since he also has Kanon who often clings to him, he also tells Rina that he feels kinda happy because it likes he has another little sister. Hearing what Kazuya said, Rina blushes. After that, they go to the theme park and play a lot.
After awhile, Erina becomes cranky because she's hungry, so they go to the a spot on the park where visitors are allowed to eat there since Rina says she has prepared a lunch box for three of them. When eating Rina's cooking, Kazuya praises Rina that she will be a great mother in the future, and once again it makes Rina's face very red. Kazuya asks what happen with her and she said that just now she imagines that the three of them are look like a newlywed family. And now it's Kazuya's turn to blush too thinking the same thing, plus he just realized the reason why Rina blushed before when he said Erina looks like his new little sister, because if they were married than Eria would really become Kazuya's little sister.
Shortly after they finished eating lunch, Erina falls asleep. Kazuya then suddenly calls Rina by her name (he usually calls her by her family name, "Yunoki-san"), startling her. He says it's just like before when they played dart and billiard where Rina called Kazuya by "Darts Master" and "Nine Breaker", and now if he calsl her by her name it sounds more like newlywed couple. Rina then starts calling Kazuya with "anata" too after that (roughly "dear"; by the way on the game you can ask Rina to call you "darling", "goshoujin-sama", or one other option I forgot).
Kazuya asks Rina what they should do now Erina asleep. Rina says that Erina usually hard to awake once she falls asleep so she suggests to take Erina to children care facility on the theme park so the two of them can go to attraction they couldn't go to before like jet coaster. Kazuya agrees so then he carries Erina on her back. On the game though, there's additional scene where Kazuya and Rina go to the Zombie House attraction, and Rina is very scared because she's weak against ghost and those kinds of thing.
On the way back, Kazuya says he really enjoy today, and the lunch box Rina made is very tasty too since they ate together. Rina agrees and then it gives Kazuya idea, which is for Rina's cooking club to hold a lunch box event on the upcoming school festival where everyone can bring their own lunch box and eat it together. It can also attract students to join Rina's cooking club, Kazuya also says they can ask Kanon and Nonoka and other girls to participate too. Rina thinks Kazuya's idea is very good and she will try to realize it. After arriving at the station, Erina is starting to wake up so they bid farewell. But then Rina comes to Kazuya and whisper something to him.
"Thank you for today, a-na-ta"