"Individually, we are one drop. Together, we are an ocean."
|Partners||Shiori Miyamoto (Host)|
|Occupation||Being within Shiori|
Sealed Seireitou (バインド詩織, Fuuin Shiori), more properly called The Being Binded within Shiori's Soul (バインド詩織 (なぃめん) ウ瀞霊冬川平, Shiori no fuuin no Seizon), is a being that came into being inside Shiori Miyamoto when she was forced into becoming a Shinkūmyō by her former sensei Nagato Hiroshitaki. This being refers to itself by the given name Seiun (星雲, lit. Nebula), and states that she was born from Shiori's binded emotions and memories.
It seems that she demands respect from others and asks to be called "Lady Seiun" (人柱力様, Seiūn-sama) and her host, Shiori, be called "Lady Shiori" (詩的様, Shiōri-sama). Shiori and Seiun appear to be able to speak to each other in a much more relaxed state than Seireitou and Sanagi. Unlike Shiori, Seiun is more relaxed and confident in her abilities and persona. She will never hesitate to harm her host if it is for a just cause. She seems to be unlike that of Sanagi; She is more helpful and supportive towards Shiori, like that of a sister. Seiun tends to avoid battles, preferring to help after a fight is over, but she will step in if she thinks Shiori cannot win on her own.