To be used only for images showing one single character.
Don't use this tag if you can see other characters in the background.
Animals present in the image do not count as characters if they're not given a name and are not important to the plot of the series (so an image of a character surrounded by cats will still be tagged with Solo if the cats are just random animals).
Tip: for convenience, use the alias "SO" when adding this tag to images.
See also: Couple, Group.