Amatsu Mikaboshi
Also: Ama-no-kagaseo
Japanese: 天津甕星 or 天香香背男
Translation: August Star of Heaven or Brilliant Male
Male kami of evil and stars, specifically the pole star. I haven’t found much corroborating information about Amatsu-Mikaboshi so I would consider this a best approximation at this point.
Amatsu-Mikaboshi predates the creation of Japan and possibly any of the other Kami. In the before time Mikaboshi was an impersonal dark force. He had no physical form. Before the creation of the universe he was alone in darkness and control. The darkness was destroyed with the creation of the universe, however a remnant of it still lives in the hearts of men.
It does not appear that Amatsu Mikaboshi and came to have a singular physical form like the other kami, though demonic forces came to be associated with him. Amatsu-Mikaboshi is a force of absolute domination that feeds off the emotions of humans and if left unchecked will lead to social and emotional destruction. He is he force that twists emotions to their darker halves; love to obsession or jealousy, ambition to greed for power, etc.
The oni and amano-jaku are thought to be physical agents of Amatsu-Mikaboshi. They are created by having their dark emotions twisted and encouraged in certain ways. Oni for example are twisted by a thirst for vengeance. Amatsu-Mikaboshi ultimate goal is the destruction of everything returning to the original state of darkness that he controlled.
Dark sorcerers would invoke him for malicious intent or to control territory through magic. The idea was to embrace the dark emotions that Amatsu-Mikaboshi would engender and shamanistically control it through discipline so it could be turned to the task of establishing dominion over territory or the world.