Yosuga no SoraEdit
Episode 1 "Distant Memories" "Haruka na Kioku" (ハルカナキオク)
After the sudden death of their parents, Haruka and his twin sister Sora move to the house formerly inhabited by their late grandfather, in a small village they often visited as children. There, Haruka encounters several of the residents, some of whom are old friends, but Sora stays at home, refusing to go to school even as Haruka starts attending. Realizing that Haruka is growing more and more distant and slipping from her grasp, Sora goes to Haruka's room at night and appeals to Haruka as she removes her clothes...
Episode 7 "Sinful Maidens" "Tsumi na Otomera" (ツミナオトメラ)
This episode replays the event where Sora asks Haru to take her measurements so she can have a uniform made. The next day Nao comes over to bring Haruka some mosquito repellent, since Sora is scared of mosquitoes, and then leaves almost immediately. The next day Ryouhei invites Haruka to the school rooftop to take a peek at the girls cleaning the pool. Haruka warns Ryouhei, though, not to peek at Nao, and leaves. Much later Ryouhei tells Nao that Haruka, “the prince she has been waiting for,” has a crush on her; but she thinks he does not like her. The truth is that something happened between the two many summers ago: Nao, trying to escape the noise of her arguing parents, ran to Haruka's house. At that time Haruka was sleeping at their veranda, and was surprised to see Nao on top of him with her clothes undone. Until now Nao feels guilty for what she did. However, Ryouhei, even Akira and Kazuha, is into the act of bringing Haruka and Nao together. They did so by making the two meet at school pool on a Sunday. When they were changing after the swimming lesson, Haruka rushes into the girls' locker room when Nao was scared by a black cat inside a box. The school supervisor hears their chatter, but the two were able to hide inside a box before he catches them. Thinking it was just the cat, he leaves. There, Nao gets to know that Haruka does not hate her, only that he was just surprised at the events of that summer day, dispelling her assumptions. Meanwhile, Sora shows her hatred of Nao, whom she thinks is the reason why Haruka has been preoccupied the past couple of days, at home on her laptop.
Episode 8 "Darkened Sky" "Nao Kuraki Sora" (ナオクラキソラ)
By now Sora is showing her hatred of Nao in the open, even in front of Ryohei and Nao herself. One afternoon Sora, attracted by the smell of curry cooking in the kitchen, catches Haruka and Nao making love in the living room. Sora throws Nao out of the house, warning her not to see Haruka ever again, since it is the second time she catches the two doing the "dirty deed." She then throws the curry they cooked down the drain, as she only wants Haruka's cooking. Nao is desolate after that, and though she wants to see Haruka, she has to hide because Sora is always nearby. However, Haruka is always optimistic Sora will forgive and accept them both, as he, after knowing from Ryouhei that she changed, wants Nao to return to being a cheerful, caring, and lighthearted person. Sora lightens up a bit to the sight of Haruka and Nao being together, but still has some resistance, and prefers to distance herself from the two. It is for this reason that she never joined Haruka and Nao along with Ryouhei, Kazuha, Akira, and Motoka for the annual summer trip to the beach.
Episode 9 "Distant Feelings" "Haruka na Omoi" (ハルカナオモイ)
Sora decides to follow everyone at the beach, but at the moment she got off the bus, she heard news of a young man that was rescued from drowning unconscious. As Sora looks over, she finds out that the boy in question is Haruka. However, Nao acted quickly and performed mouth-to-mouth resuscitation. With that event, Sora becomes even more insecure, eventually telling Haruka not to leave home and tells all sorts of excuses just to make him stay. One day, Sora made Haruka choose between her and Nao, but he just shrugs it off and proceeds to school with Nao as if nothing is wrong. That afternoon Haruka finds Sora missing after receiving a text from her saying "Let's leave here." Akira, Kazuha, and Ryouhei joins Nao and Haruka in search of her, until, amidst the rain, Nao finds Sora at the bus stop. Refusing to go with Nao, Sora runs out of the bus stop, angrily telling her that she is the reason why Haruka has changed. Suddenly, a bolt of lightning strikes the bus stop and burst into flames. Sora then remembers she forgot her stuffed bunny inside. Nao rushes in to retrieve the only memento Sora has of her mother, causing her to be nearly trapped inside. After receiving the rescued item, Sora reveals to Nao her insecurities with her, that she is afraid Haruka would leave her alone. The next night, Sora joins everyone during the Summer Festival at the shrine. This time, Sora is more receptive of Nao.
Episode 10 "As for a Bird's Faked Cry" "Tori no Sorane wa" (トリノソラネハ)
This episode replays to the event where Haruka is trying to talk to Sora about his relationship with Nao, but this time Sora is always at the back of his mind, since, lately, she seems not to accept Nao, and that she seems to be teasing him. Haruka suggests a date with Nao, but cannot get to tell Sora about it, even disguising it as if he will be spending time with Ryouhei. During the date, though, Nao notices that Sora is never far from Haruka’s mind, him buying things for his sister rather than for her, and eventually spoiling their date. They plan to make croquette curry upon arriving home, but is canceled when Haruka finds Sora not feeling well in her room after having a bad dream. The next day Nao notices that Haruka tries to hide his date with her from Sora, but she just went along. One night, Haruka catches Sora masturbating in her room while mentioning his name, much to his dismay—she is enamored with him ever since that one summer day in their childhood when Haruka kissed Sora while playing.
Episode 11 "The Uncertain Pair" "Sorameku Futari" (ソラメクフタリ)
Haruka takes Nao on a date again, but he cannot shake the sight of Sora masturbating that night off from his mind. Eventually Haruka hits his limit and tries to get rid of those thoughts by taking Nao to a love hotel, but she rejects his act and asks if he really loves her. Haruka is unable to answer and returns home. Soon after, Sora gets a fever and Haruka stays home to take care of her. That evening, Sora, with her fever subsided, confesses her feelings to Haruka and the two make love, beginning a relationship. This did not go unnoticed, as everyone, especially Kozue and Nao, begins to see the twins spend more and more time with each other. One afternoon, when Kozue and Nao decide to visit the Kasugano residence, they catch the twins in the middle of making love.
Episode 12 "To the Distant Sky" "Haruka na Sora e" (ハルカナソラヘ)
Kozue runs away in shock at the sight of the twins making love, while Nao calmly left the scene, but Sora wouldn't even care. Haruka thinks of ditching school, but she tells him to think little of it. Kozue tells him the next day that she'll never talk to him again, while Nao effectively ends her relationship with him after his apology. That night Haruka fights with Sora when he tells her that they stop doing it, even inadvertently hitting her. Things get complicated when they find out that their parents left no money for the two, and in order to survive they have to be taken under custody of their relatives, but this means them living apart. That afternoon Haruka awakens to find Sora missing and her room in a mess. He goes looking for her after receiving a text from Sora which sounds like a suicide note. Nao even helps him in looking for her everywhere, mentioning to him about her confrontation with Sora, saying she has seen the two making love that summer day, and that "now they are even." Haruka then remembered the lake Akira mentioned the other day. Haruka finds Sora, and his attempt to stop her from going deeper in to the lake nearly ends in them drowning. Days later the two leave the place to live together overseas in the city where an artisan who had connections with their parents lived, hoping to find happiness elsewhere. Even though Kozue is unwilling to accept them, Nao believes they will do just fine.
- Sora harbors great resentment for Nao and her over-too-familiar attitude towards her brother, who seems divided between his devotion to the two girls.
- Nao’s compassion and maturity projects a sense of sisterly love towards others, though for Haruka there is a deeper and more intimately sensual feeling.
- When the Kasugano twins last visited the area, their departure was particularly painful for Nao, who had grown quite close to Haruka, to the point of having sex with him on one occasion, about which she still feels guilty.
- Upon their return, Nao attempts to rekindle their former close relationship.
- Sora's strong bond with her brother, strengthened as a result of the tragic loss of their parents, leads her to fantasising about incest and she goes to great lengths to seduce him or at least to get him to spend more time with her.
- Sora hates Nao, although it is implied that they were once good friends. She is often seen clinging to a stuffed rabbit toy, which she received as a present from Haruka before they left for the village and which lends her a deceptively childlike character.
- The series depicts alternate 'what if' storylines in which Haruka engages in romantic and sexual relationships with the heroines of the story; but little is given about the lasting or more profound impact of his casual attitudes towards sexual involvement, lending him a rather rakish character.
- This is the first (and possibly only) love triangle in the anime.