User blog comment:Serza5/Macne Roro/@comment-32500188-20140704181851/@comment-3076833-20140704192227

A headcanon is like something you think a character will do/has but it isn't official.

For example the headcanon here is that Roro is part of the Macne family although he isn't officially, but Momo thinks it's a good trait for him.