Saiun (犀云, Saiun) is one of Takemikazuchi’s shinki.
Saiun is a young man appearing to be in his mid to late twenties. Like all of Takemikazuchi's shinki, he wears Shinto priest robes, and his hair is mostly loose with some locks pulled back into a ponytail at the back of his head. His official coloring as a human is unrevealed, but based on shading his hair appears to be brunette or black.
As a vessel, Saiun takes the form of Takemikazuchi's divine garments that he wears during battle. This mainly consists of a charcoal gray (in the manga) or indigo (in the anime) kimono over black undergarments, with leather boots and a tiger fur haramaki.
Saiun is loyal to Takemikazuchi, to the extent that he always apologizes when he allows Takemikazuchi to be injured.
Chapter 35: Death Saiun is present in his vessel form as Takemikazuchi's battle gear, although he is not introduced or named as a human.
Chapter 61: Renegade Saiun's human form is revealed, standing behind Kiun while Takemikazuchi warns him not to damage the Near Shore.
Chapter 62: Pride, Collide, Untied Saiun gets upset when Yukine and Yato mock them, but settles down when Kiun tells them that they should show respect and avoid belittling their enemies.
Chapter 63: Ecstasy Holding his abdominal wound inflicted by Yukine, Saiun apologizes to Takemikazuchi for allowing him to be injured. Takemikazuchi reassures him that he has no reason to apologize; this is Saiun's first time ever being damaged, and he is holding up very well against a hafuri.
Chapter 66: Smoldering Sparks Miun looks worried when Kiun is deeply cut by Yato, and sympathetic after Takemikazuchi scolds him for missing an opportunity to become a hafuri.
Chapter 67: Mine Saiun holds Kaun in his lap after the latter is nearly shattered by Sekki. Yato remarks that Takemikazuchi's shinki are no longer following him, including Saiun who has sustained two more injuries during the fight.
Chapter 68: The Road Home Takemikazuchi reverts Saiun to his human form, along with Miun and Kaun. He is shown slumped over with Miun helping him stay upright. Miun also helps him walk home after the three of them and Sekiun are sent home.
Chapter 75: And Then He... Saiun is present in his vessel form when Takemikazuchi arrives at Kofuku's house. He helps in performing Yukine's second ablution ceremony. He has sympathy for Yukine, remarking to himself that Yukine really has it rough. After the ablution is complete, Takemikazuchi commends her, Kaun, and Saiun, and sends them home.
Chapter 80: Inciteful Saiun comes with Takemikazuchi to help fix Kofuku's roof. He and Kaun talk about how it may be unlucky entering the goddess of poverty's home, with Saiun saying that doom is already upon them.
- Saiun's haramaki is mistakenly drawn with spotted fur in Chapter 35 and Aragoto Episode 12. It is corrected to tiger print, as is common for Japanese thunder gods to wear, in Chapter 61.
- The kanji used for his name (犀) means "rhinoceros". It does not have a kun reading, so both his human and vessel names use its on reading, "sai".