Seiryū

is a snake demon who worked under Hoshiyomi to recover the Naginata of Kenkon. Seiryu and the other ninjas were eventually killed by Miroku's Kazaana.

When he first appeared, he called himself Seiryu of the moon.

Appearance
Seiryu has scaly gray skin, with yellow eyes accented with dark markings. He wears a black shinobi shozoku with a mask. After his transformation, he has medium-length spiky dark green hair with a gray headband with a crescent moon in the forehead. He wears dark blue and black armor tied together with a lavender sash.

Abilities

 * Shuriken: Seiryu had once used a shuriken to prevent Inuyasha from escaping.
 * Enhanced Speed: Seiryu moves so quickly that he appears as a shadow.
 * Demon Ninja Doppleganger Technique: The ninjas move so quickly they create shadow-like dopplegangers of themselves.
 * Demon Ninja Darkness Puppets: Seiryu had indirectly controlled on of the puppets created by Genbu.
 * Transformation: Seiryu changes his appearance in his fight with Sango. In this form, he has dark green hair. He doesn't use any of his other ninja techniques in this form.
 * Demon Ninja Battle Scales: Seiryu had lifted scales off his body and caused them to flurry about.
 * Demon Ninja Scale Storm: Seiryu launches his scales at his opponents. He used this move to trap Sango in a whirlwind of cutting scales.

Personality
Seiryu appears to be impatient and violent, shown when he and the other ninjas were spying on Kagome and Akitoki, and he was more interested in killing them than actually taking the blade. It can also be assumed that he's a pervert, as when he was fighting Sango he went so far as to flirt with her and make sexual innuendos.

Quotes

 * "Look, those humans are defenseless. This is our chance to attack them and take the Ken blade!"
 * "I'm Seiryu of the moon. The pleasure's all mine."
 * "I'll tear apart the woman."
 * "You smell tasty, young miss."
 * "Let's kill them now and get it over with."
 * "Please do not worry. Rest assured. I shall take care of your body."

Trivia
Hoshiyomi's four Ninja underlings are representations of the four Mythical Creatures of Chinese Culture: Dragon, Tiger, Phoenix, and Turtle. The shitoshin (Four war gods) of Horai Island also share this likeness in their appearance. http://en.wikipedia.org/wiki/Four_Symbols_(Chinese_constellation) Also, the same four names are used for The Four Beasts, who were villains in the first season of the anime Yu Yu Hakusho.