So Yukiko's story mode in P4A questions:
This ending isn't canon, is it? Or did I get a bad ending? I mean her story mode was only 9 chapters, explained jack shit, and ended in a comedic scene of agony as she lost her mind and forced everyone to eat her food. Did I mess up somewhere or is that it?
You got the 'joke' ending. The 'trigger' for them pretty much come down to one single dialogue choice. You should have chosen not to look at the box lunches for the 'real' ending.