Seishuu's main feature is his hair, which is made of snakes. He's taller than an ordinary person, has pointed ears, wears the Kou's traditional clothing, and has a shoulder protector on his right shoulder.
Seishuu has a slight outgoing personality but in most cases, he has an intimidating and fearsome expression on his face, along with the other Household Members of Kouen. He is usually seen with Kin Gaku and tends to tease him a little but ends up getting smacked on the head for his words. Seishuu is extremely loyal to Kouen and would do anything for him, even as to pick up the clothes that Kouen threw during Alibaba's visit to Balbadd. He was even shocked when he heard Kouen laugh and commented that it would be the first and last time Kouen would laugh.
Seishuu attends the Emperor's funeral and is located with the rest of the court, with the traditional mourning attire.
When a priest reads the testament and Gyokuen Ren is appointed the next Emperor, he, Shou En, Kin Gaku and Kokuton Shuu rise up, enraged, because Kouen was supposed to be the next Emperor. Seishuu and the others listen at Gyokuen's explanation of her being the next Emperor instead of Kouen, but they know they have been fooled. Immediately after that, the court splits into two, with Gyokuen and the Imperial Priests on one side, and the army and the Imperial Family on the other.
Alibaba Saluja is fighting against the Black Djinn, and is about to use his Extreme Magic to eliminate them when Shou En advances his move and destroys them with a breath of fire. After that, Kouen and the other monsters make their appearance riding carpets. Kouen analyzes the situation and, when he sees Kouha Ren's state, he says to his Household that if the the enemies are too much for the others, they will deal with them with their strength. The four monsters roar in approval.
Seishuu, Kin Gaku and Kokuton Shuu head towards the Black Djinn. Seishuu says to Kokuton and Kin that they have to take the Black Djinn down on their own for not to make Kouen's hands get dirty with their filthy blood. Kin hits him on the head, and asks why is Seishuu giving orders, calling him fucking snake brat. Seishuu complains, saying that this hurts. Then, they activate their Household and become huge monsters. With the snakes of his hair he catches and shatters the Black Djinn.
After Alibaba has introduced himself as the former third Prince of Balbadd and his history reveals him to be protected by Sindria and Seven Seas Alliance, Seishuu comments that this makes him an enemy. Then, Alibaba proclaims that he has stepped on the battlefield in order to protect the third Prince, Kouha. All the soldiers are astonished, but Seishuu only replies that this is a bluff, no matter how you look at it.
Alibaba has been ashamed by Kouen, and Seishuu is still angry, saying that this brat made use of prince Kouha to get away, and in the top of that, he didn't thank prince Kouen in their first meeting. Kin addresses to him, saying that there's no need to be resentful, since the young master didn't mind too much and that Alibaba was embarrassed. Aladdin begs Kouen to send back his soldiers, saying that won't matter if they are from Kou or Reim, they will die. Kin, Kokuton and Shou are surprised, but Seishuu asks Kouen to not be bothered by the nonsense spouted by this dirty little magician.
|“||Come, Household Born From Astaroth, I Consecrate My Body To You, Become One With Me!!||”|
- Assimilation: By saying this phrase, Seishuu takes on an even more monstrous appearance. He becomes larger, and so does the snakes he has for hair. The snakes are now able to wrap around, bite and eat things as large as a Black Djinn.
- Although he was introduced in Night 116, his name wasn't revealed until Night 182.
- His first name means Blue Beauty or Blue Excellence. His last name means Plum.
- "Seishuu" is the Japanese pronunciation; in Chinese his name would be Qīngxiù.
- His snake-like hair may be inspired by the Gorgon of Greek mythology.