what do main character demons in japanese anime look like, what are their powers, and post your favorite pic of any?

Well, um, there's Ryuk the Shinigami. His power is killing people by writing their name in his Death Note and flying and walking through walls.

It depends on what the mangaka want the demon to look like.. ^^

For example.. There's Rin Okumura from Ao no Exorcist. <3 He has this sword that makes his true powers come out. (Hard to explain) He's the son of satin, but hides it.. ^^

Kenshin's battousai manslayer form is quiet demon-ish. He is the main character of Rurouni Kenshin. And his power is killing. But, Kenshin has turned a new leaf and has decided never to kill again, though temptation and pressure from other manslayers often disrupts his transformation process. Kenshin won't allow anyone to hurt his new family: Kaoru, Sanousuke, or Yahiko

Fairy Tail Mirajane / The Demon Mira
Magic:Darkness Magic
Lightning Magic (Anime Only)
Sleep Magic
Take Over
Transformation
Water Magic

A shinigami this one certainly looks kind of like a human, a shinigami's power is to kill a human being by useing it's Death Note, also a shinigami has wings.

Rem. A shinigami from Death Note.
Invisible to everyone that hasn't touched her Death Note, can kill people with Death Note, the Shinigami eyes, ect.