Relatively speaking it is an extra day which shows what happened to the characters after some time and how their relationship develops (happy end?). At the moment, only Harold has the epilogue and it is available regardless of the ending from the main menu (don't peek. choices through the main story still matters). In the future, it will be available only if you finished the game with the best ending. (for exemple Papa Bear have 3 endings: bad, neutral, best)