Third Eye | Danbooru

第三の目サードアイ

A person with a third eye on their head or body instead of the usual two. The extra eye does not have to be located on the head, but it should still be part of their body.

If the eye is not on the character's body, instead use:

disembodied linked eye, when the eye is still linked to the body in some way, such as with Komeiji Koishi or Komeiji Satori from Touhou.
disembodied eye, when the eye is fully detached from the body.