Illegal Rare

Supernatural creatures live alongside humans, but these "rares" are being hunted to extinction over time. An organization is being formed to protect these rares, and allow them to live their lives as they like. The starting members of this organization are few; there's the masked Fukumen, the Black Vampyr king AxL, and they are soon joined by the sweet-voiced mermaid Mirror. Together, they will protect the rares from the deadly hunters!

(Source: MangaHelpers)

Included one-shots:
Volume 4: Dark Pawn: Yami no Shichiya, Tsukumogami, Nurarihyon no Mago Gaiden