KissXSis

Ako decides to help Keita study in order to improve his passing rate, though both have a little trouble staying focused on the matter at hand. Ako shows Keita her chest in order to encourage him to study, but this ends up being all Keita can think about in class. Ako decides to try an alternative method, writing the notes on her body. Despite embarrassing himself in school whilst distracted, he fares better on the tests. However, when Keita likens a kiss from Ako as a penalty game, Ako gets mad and corners him, eventually making him do a wrong answer so he would have to take the penalty game. They hint at going further, but are stopped by Riko, who had been learning how to prepare food for Keita, though it ends up tasting bad. Despite this, Keita manages to improve his grade.

While Keita studies at school, Ako and Riko reminisce on when they started going to junior high, the first time they were apart from Keita. When they watched Keita perform athletics, they fell in love with him. Meanwhile, their teacher, Yūzuki Kiryū, eavesdrops on their discussions and begins to worry about what is going on with them. After studying, Keita runs into Ako and Riko at the shrine, where they were praying for his success. He remembers when he was young and prayed to marry both Ako and Riko, only to be told by his father that polygamy is illegal. Keita makes his wish and the three return together.

Unable to view and get porn from the internet using a PC their father won at a raffle, Ako and Riko decides to buy erotic games in Akihabara. But in the process Keita has to accompany them, so they devise a way to hide their real purpose for going to Akihabara. Ako distracts Keita by taking him to a cosplay shop whilst Riko investigates the 18+ section of a game shop. Whilst changing, they run into Akos teacher, Yūzuki, who is a closet otaku (dressed as Mahoro from Mahoromatic Maiden). Riko later encounters her whilst trying to get a special edition game. After meeting Keita and being reminded about Ako and Rikos crush on him, Yūzuki drags him off to talk to him, inadvertently taking him to a cosplay-themed love hotel. After later being found by Ako and Riko, the group are encountered by Keitas kōhai and Yūzukis younger sister Mikazuki, who covers for Yūzuki by stating she was buying the game for her.

The summer festival comes, and it will be the only day Keita will be free from all the prep school work. This means that Ako and Riko will be competing for a night at the festival with him, although they all go to the festival together. But a few incidents involving paraders enables Ako and Riko to indeed spend some time with Keita alone. They also had to contend with Kiryu-sensei (who was patrolling the fair and catches Riko and Keita in the forest), Mikazuki, who is Miss Mikoshi, and a (ahem, naughty) chick that Ako bought that caused Keita to see Miharu peeing in the bushes. Shocked, Miharu drops on the ground what seems to be a love letter.

With Keita ill before the big exams Ako and Riko step up to the mark by getting out of school and making Keita feel better by nursing him back to health, but a slow recovery is the last thing Keita wants as his two stepsisters fight for the place closest to his heart. Both of them end up licking the sweat off his body, which passes the cold over to them whilst Keita makes a full recovery. The final exams are overseen by Yūzuki, who is surprised to find Keita there. Whilst Keita takes his exams, Ako and Riko remember how Keita was there for them when they were taking their exams. After returning from his exams, Keita gives his thanks to a sleeping Ako and Riko, who are surprised about it once he leaves.

After Keitas graduation, Ako and Riko arrive to find they were too late to get the second, or any button, off of Keitas blazer. They decide to, against Keitas will, hold a draw for consolation prizes from Keita, with them, Mikazuki and Miharu as participants. Akos hope backfires and ends up getting Keitas shirt collar, Mikazuki wins the opportunity for Keita to flip her skirt, though he is unaware she wasnt wearing any underwear. Riko wins a chance to kiss Keita in front of everyone, but is too embarrassed to do it. Miharu gets the remaining prize, to spend ten minutes in the equipment room alone with Keita to do anything. Keita simply uses the time to thank Miharu, but after a slip up, they end up in a compromising position, leading Ako and Riko to assume the worst. Later that night whilst Keita goes to sleep, Ako and Riko make a move on him, though this just gives Keita weird dreams.