Ketsueki no Iro wa... Character Profiles Vol.3

Now, to profile the siblings of the main protagonist (you), Inoue Kyashi:

Inoue Rissa

Rissa is Kyashi's younger sister (two years younger) who attends the Public High School as a First Year. Her best friend is a blue-haired girl named Sekisetsu Suiko (a pseudonym), who is virtually obsessed with water. Rissa hates her mother for suddenly leaving one day almost a year before the game starts, and hates her twin brother even more for the same reason. Her dream is to one day become a doctor, so she has a massive collection of medical textbooks.

She is rarely seen without the ankh around her neck, a souvenir of a trip to Egypt when she was little, and the last remaining memory of her father, who died when she was 6. Though she isn't aware of it at the start of the game, Rissa is actually a fairly-powerful magical girl.

Inoue Rai

Rai, Rissa's older twin brother, attends the Private High School, and takes advantage of its boarding option, meaning he lives there. He has a job working at the convenience store near the school complexes, which allows him to sustain himself. The reason he uses this situation is to alleviate financial pressure off of his sisters, since the three were barely managing to survive until Rai and Rissa entered high school. The original plan was for all of them to attend the Private High School, but the severe lack of funds made it so only one of them could attend. Kyashi and Rissa both agreed that Rai (the only academically-focused one of the siblings) deserved it, so Kyashi transferred to the Public High School, the same place that Rissa had enrolled in.
Rai is blind in his left eye. When he was leaving, Rissa got very angry at him, accusing him of being "just like their mother", and punched him (rather hard) in the face, causing permanent damage to his eye, which rapidly lost all sight.