|Height||168 cm / 5'6"|
|Eye Color||Light Brown|
|Date of Birth||July 9th, 1982|
|Other Relations||Akio Kano (Acquaintance)|
|Affiliation||MPD Public Safety (Division 5, F Squad)|
|Hometown||Takasaki, Gunma Prefecture|
|Manga Debut||Line 3; Merry Christmas|
|Anime Debut||Episode 2; Safe House|
|Japanese VA||Satoshi Hino|
|English VA||John Ramirez|
Ryusei Yanagi (柳 劉生, Yanagi Ryūsei?) is the doctor attached to F Squad specializing in the hemotology of the redeye race. His job is to watch over the devils in F Squad and keep them healthy by giving them check-ups and providing sedatives. He originally worked at the Tokyo Metropolitan Karasuma Hospital. He was apparently a punk in his youth.
Yanagi is a man in his early thirties with an average build and considerably shorter height. He wears oval-shaped glasses over his light brown eyes, and his black hair is distinctively kept shaved.
Yanagi is a very calm and level-headed man. He is very knowledgeable about devils, and does his best to keep the devils in his squad healthy. He is very serious about that job and sympathizes with devils. He is kind caring as he takes other peoples feelings to heart and consideration at all time, and he also tries to help out others as much as possible. However, when he becomes provoked by others or becomes upset, he will become rough and angry, making his traits from his younger days as an apparent punk visible.
- The name Ryusei means "ax, butcher, assassinate, weapon of war, logging axe, kill en masse, peeling (paint off a wall, etc), sparse, faded" (劉) (ryu) and "life, living" (生) (sei).
- Ryusei's surname Yanagi means "willow" (柳).
- Apparently, Yanagi's dialect comes out when he's talking with his wife who's from the same town.