Seiryuu is a tall, elderly man with long, white hair, a beard and a mustache. He has a patch over his left eye and a scar on his left cheek. He wears traditional clothing and armor, as well as a small hat.
Seiryuu is a stone-faced and stern person, yet he's very loyal to the First Emperor Hakutoku which is later served his surviving son, Hakuryuu Ren, in his campaign.
Seiryuu's first appearance is alongside that of Kouen Ren. He and the Left General, Kokuhyou Shuu, are standing at the army's base in Balbadd, in front of the throne where Kouen is sitting, waiting for Judar's return. When Judar comes in, along with Koumei Ren and Kouha Ren, Seiryuu questions Judar, asking how dare he keep Kouen waiting.
By his position and age it's assumed that he has great military skill and experience.
- Assimilation: Seiryuu transforms into a monstrous and ferocious form. Seiryuu can make allies turn against each other thanks to Belial's abilities by using his third eye located on his chest. However, it is shown that a magician's Borg is enough to protect against it.
When Hakuryuu decided to make a rebellion again Kouen Ren, both him and Kokuhyou Shuu decided to follow him because they were the trustful subordinates of king Hakutoku Ren so they believed that Hakuryuu is the true successor
- His first name means Blue Dragon. His last name means Plum.
- "Seiryuu" is the Japanese pronunciation; in Chinese his name would be Qīnglóng.
- He shares the same family name as Seisyun Ri and Seishuu Ri.