; :Tsukiko is the heroine of the
Starry☆Sky games. She is the first female student to attend Seigetsu Academy, a traditionally all-boys school, and is in her second year.
Spring ; :Yoh represents
Capricorn. His French name is Henri Samuel Jean Aimée. He is half-French and was often teased for that as a kid. He met Tsukiko when he was young, and because she was the only person who didn't make fun of him for being half-French, he fell in love with her and asked his father to let him transfer to Seigetsu Academy in order to pursue her. Initially disdainful of everyone except Tsukiko, eventually, he learns the importance of having friends. His father hopes to work in America to develop a special astronomy project. He is in his second year at the school. ; :Kanata, also a student in his second year, represents
Pisces. Brash and impulsive, he has been friends with Tsukiko since childhood and has developed feelings for her. He does not get along very well with Yoh. Kanata has a terminal illness that leaves him in a lethargic state, which is why he often skips classes and faints without reason. However, he refuses to seek medical help and often gets involved in school fights that worsen his health to protect Tsukiko. ; :Suzuya represents
Cancer. Calm and friendly, he was friends with Tsukiko and Kanata since childhood and often watches out for them like an older brother. He is very good at cooking and often uses the school's kitchen to prepare food for his friends. Suzuya is also in love with Tsukiko, but because he knows that Kanata also loves her, he holds back. Beneath his warm exterior, Suzuya has a dark side and worries about Tsukiko constantly. He is in his second year as well.
Summer ; :Azusa represents
Sagittarius. Although he is a newcomer to the archery club, he has met Tsukiko before and inspired her to become better at it. He is a deadpan-like, cold, serious, introvert, plain, calm, quiet, and stoic with not too much to says, only just himself was can be a little bit more expressive and emotional. While he appears confident, even to the point of overt boasting, but he is actually quite insecure/uncomfortable and struggles to make a real effort to achieve his goals. He is revealed as a distant relatives of Tsubasa, whose more
comical relief-like, optimistic, hyperactive, and mischievous personality (cheerful, energetic, extrovert, warm, gentle, laid-back), starkly contrasts with him. He has a
emo-like yet "effeminate" (androgynous) appearance that becomes especially obvious, just when if he is between (around) other boys only. Azusa often flirts with Tsukiko, and his actions annoy Ryunosuke. He is a first year. ; :Homare represents
Taurus. He is the captain of the archery club. He is openly friendly and often settles arguments between Ryunosuke and Azusa, but is prone to feel pressured for the success of the archery club. He is in his third year. His best friends are Shiranui Kazuki and Shirogane Oushirou from the same year. ; :Ryunosuke represents
Scorpio. He is the sub-captain of the archery club. He appears to be serious and calm but hides a penchant for sweets. Ryunosuke has kept an eye out for Tsukiko ever since he first saw her. He is in his second year.
Autumn ; :Naoshi represents
Leo. He is Tsukiko's homeroom teacher and the advisor for the archery club. He is energetic and enjoys the "youth" part of high school since he spent high school mostly studying, and because of that, a lot of students can't take him seriously and often play pranks on him. Naoshi's best friend, Hiroki, got him to enjoy high school, but Hiroki was hit by a car saving the girl he liked. Because of that, he was afraid to fall in love until he met Tsukiko. ; :Iku represents
Gemini. He is currently a student teacher and friends with the school nurse, Kotarou, since they were children. Iku and his twin sister Yui were both born with poor health, and Yui died while they were in high school. He was formerly the lead singer of a band the heroine liked but destroyed his voice while overworking himself due to the pain of his sister's death. His band members turned out to be using him for money and promptly dismissed him when he could no longer sing. Iku lost trust in everyone until a girl, Tsukiko, helped him gain it back. ; :Kotarou represents
Libra. He is the school nurse who once had ambitions to become a doctor. Iku's sister, Yui, had feelings for him, but after her death, Kotarou blamed himself for not being able to save her. His father is the chairman of the academy, but after his father's retirement, the position was given to Kotarou's sister, Koharu. However, he ended up obtaining the position due to Koharu's wish to work overseas.
Winter ; :Kazuki represents
Aries. He is the president of the student council. He is gifted with the power of foresight, although this ability does not allow him to see everything. He blames himself for the death of his parents because of his lack of understanding of his own power. Because of this, he hates his power. As a child, he was often involved in fights to prove his own strength. The day he met Tsukiko, she told him that only people who think they are weak try and show their strength through brute force. He had become friends with her, and Kanata and Suzuya as well. He is in his third year (apparently he repeated a year, together with Shirogane) ; :Tsubasa represents
Aquarius. He is the treasurer of the student council. He often lights up the mood in the student council. However, he is emotionally unstable. At a very young age, he was abandoned by his parents, who got divorced. He was taken in by his grandparents on his mother's side. When Tsubasa was young, he spent a lot of time with his grandfather, and they often made inventions together. Even now, Tsubasa still likes to invent things. His grandfather's dying wish made Tsubasa promise to take care of his grandmother. His grandmother sent Tsubasa away to school, and ever since Tsubasa likes to be alone. He thinks that being alone is better than being with people because he is afraid of losing things that are important to him. He is a first year. ; :Hayato represents
Virgo. He is the vice president of the student council. He comes from a well-known family of pianists but lacks self-confidence and feels pressured to be up to par with his family's talent. In the end, he decided to leave his house and stay in the school dorm. He is a second-year student.
Special character ; :Represents Ophiuchus, the 13th constellation. This special "13th Character" was introduced in the 13th secret date CD. Not much information is given. His Greek name translates to “serpent-bearer” and he is often seen holding an albino snake in many official illustrations. In the fourth game Starry Sky in Winter it's mentioned that he has greater, stranger power than Kazuki Shiranui.
Minor characters ; :, , and are members of the archery club and are dubbed as the "idiot trio". ; :Oushirou is an acquaintance of Kazuki's and Homare's, he carries a camera everywhere due to being a journalist for the school paper. He is a third-year student. ; :Izumi is a first-year student in the Mythology department who appears in the After Spring game. He has a serious and straightforward personality despite his devil-may-care appearance. He tends to act on his thoughts, does not think very deeply, and does not lie either. Despite coming from a yakuza background, he is a pacifist at heart and is weak at fighting. ; :Oshinari is a student teacher who appears in the After-Spring game. When he is free, he helps out at the dormitories. ; :The name of this character is changeable. Haruna appears in the After Spring, Summer, and Autumn games. She is a boyish character whom the protagonist relies on for advice.
Family ; :Yoh's father is French. He often teases Yoh for fun. Yoh's father has a cheerful personality. He tends to dote on his wife to the point that he sometimes forgets about Yoh's existence. ; :Yoh's mother. She actually knows the protagonist's mother as they were classmates. She and her husband are still passionately in love. ; :Kanata's mother. Despite her coarse language, she is good at looking after others. After her husband's death, she raised Kanata by herself. Although she hits Kanata quite often, she pampers the protagonist and Suzuya, and thinks of them like her own children. ; :Suzuya's mother. As the result of being the only housewife within the three families in
After Spring, she is the one who looks after the children the longest. Her husband is a salaryman and is not shown in the game. ==Development==