Spoilers

From http://game14.2ch.net/test/read.cgi/gamerpg/1215781615/

I cannot prove their authenticity. Read with your own discretion

• There are three endings, 2 bad, 1 good
• The final boss fights happens on 12/23, so this game, like P3, may not span for a whole year
• The split of the ending seems to happen on 12/3. That day the player will have to make a key decision
• In one of the bad ending Nanako will die
• Max social link seems to lead to the good ending
• There is also special conversation with the maxed social link character, like FES
• The main has some sort of separation after the game, not sure if it's death or leaving the town