| Sora Kasugano|
|First Appearance||(Anime) Episode 1|
|Portrayed By|| |
Sora Kasugano is one of Yosuga no Sora heroines. She has a twin brother and is very dependent of him. Sora couldn't care less of what others think, and would rather surf the Internet and eat instant foods, so long as Haruka is always by her side.
She is a quiet, fragile and reclusive girl, fraternal twin sister to the protagonist. Yet beneath Sora's angelic doll-like appearance lies a troublesome personality that’s prone to withdrawn laziness and demonstrates a rather severe lack of social graces. In episode 10, she becomes more considerate and caring towards Haruka after she decided to not trouble Haru too much and tries her best to take care of him.
Sora has gray eyes and silver hair. She has a perfect doll-like appearance and is often seen as a fragile and weak girl. When she goes to school (Or some other places) she use twintail hairstyle, she just untie her hair when she's at home. She is 152 cm tall and is often seen carrying a rabbit doll, which she received as a present from her mother before she and Haruka left the village and which lends her a deceptively childlike character.
The traumatic loss of their parents, her deep bond with Haruka and a kiss she shared with him as children causes her to fantasize about him. While she shields the extent of her feelings for him in public, she experiments with herself while fantasizing about being with him. She hates Nao because of her relationship with Haruka and the fact that Nao seduced Haru when they were young. Although she hates Nao, it was implied that they were once good friends.
At the end, in her route, she wins Haru's affection by confessing her love to him and making love to him as he was caring for her when she had a fever. After they got caught making love by Nao and Kozue, he attempted to break off the relationship and she attempted suicide. Haruka tried to save her but he only caused she and he to sink. They were saved by Nao (As it was hinted on the ending) and afterwards, they decide to travel to a far away country, promising their friends to come back with souvenirs.
- Mr. Kasugano (father) (deceased)
- Mrs. Kasugano (mother) (deceased)
- Haruka Kasugano (elder twin brother)
- Grandparents (mentioned)
- Kasugano distant family relatives (mentioned in episode 12)
- Nao Yorihime (They were friends in the past but Sora caught Nao having sex with Haru, which is the reason why she hates her.)
- Ryouhei Nakazato
- Akira Amatsume
- Kazuha Migiwa
- Motoka Nogisaka
- Kozue Kuranaga
- Like Motoka, she seems to have a high libido, proven by the fact after the first time she made love with Haruka, she was eager to do it 'many times again'.
- She has an irrational fear of mosquitoes as displayed by her attempt to kill one with hair spray.
- She is portrayed as heavily dependent on Haruka in the beginning.
- She is almost never seen without her stuffed rabbit doll that her mother gave her when she was hospitalized. (Anime)
- She is the only character who has attempted suicide.
- She goes to great lengths to seduce Haruka or at least to get his attention.
- She spends most of her time surfing the internet. Haruka describes it by saying "She can't live without it".
- She enjoys consuming chips and other various snacks as well as instant foods.
- She seems to like Pocky as shown in the opening scene in both the Anime and the Visual Novel where she, with Haruka both enjoys a box together.
- She is the only anti-social character of Yosuga no Sora.
- She is the only character to get married and become pregnant.