Sidoh (シドウ, Shidō) is the Shinigami whose Death Note is stolen by Ryuk. By the time he realizes this, however, the note has already changed hands several times, ending up in the hands of Mello's gang (more specifically, Mello's subordinate, Jack Neylon).
Appearance
Sidoh in the games
Sidoh wears heavy clothing that obscures most of his features, and his head is wrapped in bandages. His mouth is a canary's beak. Obata states that Sidoh's "arms" can be described as insect-like in the way they fold into his body. Though he has "hands", there are only three fingers on each appendage. In the video game, parts of him are brown and red while his bandages are a much brighter white.
Character
Sidoh in the second opening
Sidoh has a great liking for chocolate, just like Ryuk does for apples, a taste he shares with Mello. Death Note 13: How to Read describes him as "cowardly," being intimidated by Mello despite the fact that Mello is a human.
Plot
Sidoh eating chocolate
With a short lifespan remaining, Sidoh hopes to find his Death Note quickly. After repeatedly hounding Ryuk for the return of his notebook (which also involved him passing out flyers to other shinigami in the vain hope that they might recover it for him), he tracks his notebook to the Mafia. In order to regain his Death Note, Sidoh agrees to help Mello's gang against Near's SPK and the Japanese Task Force. After Light regains the Death Note from Mello, he reluctantly returns it to Sidoh to keep him from interfering and as a way of trying to retain the trust of the Task Force.
Conception
Tsugumi Ohba said that he used Sidoh as another Shinigami appearing in the human world because he liked Sidoh's appearance; Ohba described Daril Ghiroza as a "candidate" and that he wanted a "pretty pathetic" character. Sidoh was chosen over Ghiroza because her high rank made her ill-suited for being pushed around by Mello.
Ryuk being chased by Sidoh
Takeshi Obata described Sidoh as "very funny," citing the time when Sidoh becomes the first Shinigami to distribute flyers. He also claimed to have wished that Sidoh had appeared more often in the story.
Obata said that when he discovered that another Shinigami would appear on Earth, he filed through designs and nominated Sidoh and Daril Ghiroza. Obata said that he believed that Ghiroza would be chosen and prepared for that decision; instead, Ohba selected Sidoh. Obata said that he based Sidoh's design on the appearance of a bird with his mouth being based on a beak of a canary and with foldable, "insect-like" arms.