Trijask was a large built humanoid demon. His body was covered in fur, and his lower jaw was split into three sections. He had slightly sunken eyes, and he had spiked hair on his head.
Trijask was among the many demons that gathered at the Black Sabbath held by Ryo Asuka. He fuses with one of the guests at the Sabbath shortly before Akira fuses with Amon and becomes Devilman, however he is killed in the ensueing slaughter having his head split open by Akira.