Also known as: 天使と悪魔
An Angel and a Demon appearing together. This is usually done in an artistic way that shows Contrast between light and darkness, but in anime art angel/devil Yuri and Yaoi pairings are also very popular.
This tag may also apply to the shoulder angel/devil versions of characters that traditionally appear to represent the good and evil sides of a person's conscience (perhaps a Dual Persona).