|Height||178 cm (5'10")|
|Weight||64 kg (141 lbs)|
|Relatives||Naomi Osakura (wife, deceased)
Aoto Osakura (son)
|Likes||Classical music, dried persimmons|
|Dislikes||Being interrupted, too many phone calls|
|Hobbies||Reading, going for walks|
Hiryuu is a man of medium height with light brown hair and grey-blue eyes. He is frequently seen wearing navy glasses and a long labcoat, highlighting his job as a doctor. He looks younger than he is.
He tends to regard things lazily, but has incredible determination toward goals that he perceives as important. He is incredibly stubborn and is extremely competitive, once he gets going.
- Naomi Osakura - Naomi was Hiryuu's wife and the most important person in his life. She encouraged him to aim as high as he could when he was going to settle for less. Her desire to help people made him appreciate the goodness in her that he couldn't find elsewhere, and she inspired him to become a doctor to help people the way she did without even trying.
- Aoto Osakura - Aoto is Hiryuu's son; however the two have a tense and distant relationship. After Naomi's death, Hiryuu did not keep close with his son.
- Fuyuki Hibari - Hiryuu sees Fuyuki as a sort of second son, and actually shows more of his parenting to the Hibari orphans than his own son.
- Ryuuhei Akano - Their relationship is tense, and the two despise each other. Hiryuu sees Ryuuhei as frivolous, and Ryuuhei frequently tests his patience, which he has no time for.
- Madoka - Hiryuu takes a special interest in Madoka, being neither a full angel nor a human.
- Cerise St. Clair - Hiryuu appreciates Cerise's efforts to help his business. She accompanies both him and Aoto on many trips and eventually works as a secretary for the office.
- Zeno Arakawa
As a child Hiryuu was highly intelligent. He routinely scored number one in his classes and never needed to study for tests. However, his grades suffered because he didn't take school seriously; he only dedicated his time and effort to subjects he found deserving. In high school he tended to lock himself up in his room for days to get away from his parents' nagging, and eventually his parents abandoned any idea of Hiryuu making great achievements. He despised his parents after this, saying that they had only wanted him for glory.
When Hiryuu was 19, he met Naomi Nakami, a fellow student who was aspiring to be a doctor. He was immediately taken by her frail, non-threatening appearance and "sweet smile." Hiryuu was planning to get a job right after high school, or at the most attend a regular trade school. However, Naomi had high hopes for him. She encouraged him to aim higher and go to cram school, without nagging like his parents had. Hiryuu eventually  and worked toward the goal of going to the same prestigious medical school as Naomi.
Eventually Hiryuu and Naomi married. They had one child, Aoto Osakura. Naomi was the "light of [his] life" and inspired him to dedicate his life toward helping people, and for this Hiryuu was grateful. According to Hiryuu, she is the person who made him into who he is today. She was the most important person in Hiryuu's life.
One day, when Hiryuu returned from work, he found Naomi passed out on the floor. He immediately took her to the hospital, where he found that her illness had progressed to the point of no return. She woke up weaker than ever and requested that their son be brought in as well. 
Around eight years before the start of the story, in the spring, Hiryuu's wife Naomi died. Aoto was nine. The Hibari family attended the funeral. Hiryuu was devastated. As someone who saved people for a living, not being able to save his own wife made him feel he was a failure. He abandoned his practice for an entire year, forcing patients like Fuyuki to go elsewhere for their medical needs. One year later, Hiryuu reopened his medical practice, seeking a wider assortment of patients. He continued treating the Hibari family at reduced costs, as friends of the family. Mrs. Hibari died shortly after this, and Hiryuu took it upon himself to care for the family's needs, especially what Hanata could not provide.
About a year later, Hanata was involved in a serious car crash that was nearly fatal. Hiryuu was able to miraculously save him, and Hanata was indebted to him for saving his life.
Hiryuu is introduced when he calls the Hibari household to offer his condolences over the loss of his brother. He asks to meet them to bring some gifts, along with his son.