As the youngest of the court herbalists, Ryu has pretty big shoes to fill, but he works as hard as adults in his field. Specializing in plant poisons, using them to help Zen and others to develop an immunity to them, he works with Shirayuki and others in the medicinal department to ensure everyone's health in the castle.

Ryuu has a mature, calm and apathetic personality. Due to his mental intelligence, others treat him as an adult and not a child. In addition, he doesn't understand or is unable to read people's feelings at times. Because of this seemingly cold personality, many people feel wary of him, and a few rumors about him spread around the kingdom. Ryuu isn't comfortable with everyone treating him like an adult, and it seems like he wasn't able to gain many friends due to this demeanor.

With him being so quiet, his voice has a lower tone compared to other children his age and resembles the pitch of Ciel from the English dub of Black Butler, without that touch of hopelessness and mental scarring.