Shinigami no Ballad.

A girl wrapped in white, her name is Momo...in her hand lies a blunt yet shiny scythe. By her side is a wingged black cat by the name of Daniel. Carrying the souls of humans, the girl's existence parallels to that of a "Death God" or "Shinigami". At the instant when this white Death God touches the hearts of humans, the world is filled with kindness and grief...

(Source: Anime News Network)