I'm using Yanfly Message Core:Â
https://www.dropbox.com/s/i793v659eaxk77d/YEP_MessageCore.js?dl=0
I added a second font file called ComicRelief.ttf to the gamefont.css and called it "MessageFont" file then I used \fn<MessageFont> in a show text command. The first two letters were in something like Times New Roman instead of Comic Relief, but it worked for ever letter after that. The code then works for all text messages after that, with even the first two letters changing to Comic Relief. If I save the game, close it, reopen it, then load the save file, then first two letters are messed up again (this doesn't happen if I save the game and reload it without closing it).
Here's a size reduced project of what I'm talking about:Â
https://www.dropbox.com/s/fbazc7xxtamxivj/YEP%20Message%20Core%20Problem.zip?dl=0
EDIT: I used this script and it fixed it:Â
http://www.rpgmakercentral.com/topic/35332-fonts-editor-plugin/