The last (and only) stable version of media-sound/kid3 was removed from Portage, which is a violation of Gentoo keywording policy: http://devmanual.gentoo.org/keywording/index.html "When removing ebuild, ensure that you do not remove the most recent version at any given keyword level on any profile."
https://bugs.gentoo.org/show_bug.cgi?id=280790#c5