Kazuna Takashiro

Kazuna leads a normal high school life, struggling to decide if he wants to go to college or not, when he begins feeling ill. He lives under the care of a close friend of his father, Shin, and his wife, Natsuko. At school he spends some time hanging out with a girl he likes, Yaegashi. But when his illness makes the sight of blood unbearable and gives him strange dreams of his childhood, he seeks out the home where he grew up with his real parents. There he finds his older sister, Chizuna, living there, and is shocked to find that he even has a sister. Once Kazuna begins talking to Chizuna, all her talk of Takashiro's having to isolate themselves with their disease makes Kazuna drop out of school and move in with Chizuna. With his sister, he lives a lonely, frightening, and maddening life in fear of the Takashiro disease.
Appearance: Kazuna has short dark hair and a mole under his right eye.

Chizuna Takashiro

Chizuna grew up with her father after he mother passed away. She has suffered from the Takashiro disease since she was very young, and has a frail body because of it. Chizuna doesn't like socializing with anyone, and can be very curt and cruel with her words. She believes she is a danger to others and must isolate herself from the world. She occasionally attends school to kill time. She moved back into her childhood home after her fathers death, and her only visitor was her doctor and childhood friend Minase. When Kazuna finds her she sees her father in him does all she can to keep him close and dependent upon her. She has an unhealthy obsession with her father, since he saw her mother in her and kept her under his watch constantly. Chizuna has found a new reason to live in Kazuna, but knows her body is getting weaker.
Appearance: Chizuna has long dark hair and 2 moles under her left eye.

Natsuko Eda

Natsuko acted as Kazuna's mother and guardian since he was young and his father left him. She is a busy working woman, but cares a lot for Kazuna and wants to formally adopt him. She only wants him to be happy and feels helpless when he is taken away by Chizuna.
Appearance: Natsuko has short dark hair.

Shin Eda

Shin was a close friend of Kazuna's father Shizuna. He left Kazuna in the care of Shin and his wife Natsuko.
Appearance: Shin has short dark hair, glasses, and strong cheek bones.

Yaegashi

Yaegashi is an underclassmen at Kazuna's school. She enjoys painting and Kazuna often comes to visit her while she's in the art room after school. Yaegashi cares a lot for Kazuna, but soon he starts telling her to stay away from him. Yaegashi becomes unsure of herself, but in her persistence to see Kazuna, he finally has no choice but to tell her about his disease. She's concerned for him when he drops out of school and even though everyone tells her to forget about him, she refuses to let him go.
Appearance: Yaegashi has dark, unevenly cut hair that hangs around her chin.

Minase

Minase was once a patient of Shizuna's and had the opportunity to meet Chizuna when she was about 5 (and he was 16). He began to visit her a lot and wanted to become a doctor so he could study her disease and cure her. She once gave him a scar over his left eye and drank his blood. He's had strong feelings for her ever since and currently treats her for her disease and continues to study it. He's made his feelings for her clear to her, but he knows her feelings for her father are so strong that she will never love him back. His top concern is keeping Chizuna alive and has a hard time understanding when Chizuna is wreckless with her health.
Appearance: Minase has short dark hair, wears glasses, and has a scar over his left eye.

Kinoshita

Kinoshita seems to be one of Kazuna's only friends at school. He seems like a punk, but cares a lot for Kazuna's well-being.
Appearance: Kinoshita has longer, dark hair, around shoulder length.

Shizuna Takashiro
Shizuna was a doctor, and Chizuna and Kazuna's father. He's was deeply in love with his wife Momoko and knew she had a strange blood disease. He would let her drink his blood and was grief stricken when she passed away. He knew that Chizuna had the disease, but since Kazuna didn't seem to have it, put him under the care of his friends the Eda's and cut off contact with his son. He was obsessed with Chizuna since she resembled Momoko so greatly, in her looks and with her disease.
Appearance: Shizuna had short dark hair.

Momoko Takashiro

Momoko was a part of the Takashiro family, and therefore the carrier of the disease. She began having symptoms when she was 22, and eventually died from the disease. In her last years she was distant and said to have gone mad.
Appearance: Momoko had short black hair about to her chin and had a mole under her left eye.

Kazami Shinobu

Kazami was a nurse that worked under Shizuna in his last months. She later hears that he committed suicide and begins asking anyone who knows him why he would have done it. She seemed to respect and care for him greatly. Kazami manages to get her hands on some research about the Takashiro blood disease and wonders why Shizuna was so interested in studying it.
Appearance: Kazami has longish dark hair and wears glasses.