|Affiliation||Kaibara Municipal High School|
|Parents||Unnamed Father & Mother|
|Manga||Another Chapter 3.5|
Chiaki is a teenage boy who is rather tall for his age. He has a light complexion and is often seen with a natural face. He has sharp, dark-colored eyes, and light-colored, slightly spiked and cropped hair. His bangs mainly drape over the right side of his face.
Although Chiaki often holds a natural or blank face, he is a friendly young man who gets along well with people. He values teamwork, and is often seen relying on his student council members as much as they rely on him. Chiaki is one of the most responsible members of the student council and is very rarely seen slacking off. Because of this, he often looks out for his fellow student council members. While he certainly is tired of Hajime Sohma and Mutsuki Sohma's bickering and Mutsuki's tendency to slack off, he does not press on it.
Chiaki is close to his student council members as well as the other Sohmas, evidenced by the fact that he had gone to the Sohma vacation house before, as well as by the fact that he was invited to Michi Manabe's sukiyaki party. Additionally, Chiaki can have a fair amount of fun too, though his humor is mostly deadpan.
Chiaki serves as the secretary of the student council. When school started, it is mentioned that Chiaki was home, sick with a cold, and therefore couldn't come to school. He was absent for a while before finally returning to his student council duties. During his introduction, he kindly greets Sawa. He also expresses pity for Sawa for witnessing "that horror", (as in, Mutsuki's messy desk).
When Michi planned to throw a sukiyaki party, Chiaki wanted to go, but couldn't since he would have gyoza with his family anyway. He is seen helping out with the student council duties, where he acts a bit like Sawa's senior, giving her tasks and encourages her. It is mentioned that Chiaki tends to take too much responsibility, because he feels like Mutsuki is unpredictable. While he is used to Hajime and Mutsuki's bickering, he does feel like they need to work instead of slacking off.
When the student council members discussed their trip to the Sohma vacation house, Chiaki expressed that the cottage is really incredible, because the "bear Jason" lives there. Upon hearing this, Hajime is overcome with dismay.