Noi is apparently a cousin of En's. Her smoke heals almost any injury short of actual death. The closest person to Noi is Shin, as demonstrated in her revival from reptile form.
She is taller and stockier than Shin, and it surprises Fujita that she's female the first time he sees her without her mask. Noi's hair is pale blonde and her eyes appear to be red, suggesting she might be an albino. Her hair is mid length, and she has several piercings on her ears.
Noi's mask is very detailed, although dark blue and apparently vinyl-like. It is somewhat similar to the one on Shin's, although more form fitted with a zipper.