How to Unlock the Secret Ending

In Kingdom Heats 3 there is a secret ending called 'Epilogue: Lost Secrets'. To unlock it you will need to find and photograph a certain amount of Lucky Emblems, the exact number is determined by the difficulty you are playing on. If you opted for 'Beginner' difficulty at the start of the game you will need to find all 90 Lucky Emblems, if you play on 'Normal' difficulty the number will be lower and if you are playing on 'Veteran' difficulty the number is even less.

Once you have found the required number of Lucky Emblems for the setting you are playing on a pop-up should appear to notify you that you've unlocked the secret ending. To actually view the 'Lost Secrets' epilogue, you need to navigate back to the main menu and scroll down and select Theatre. If you then scroll right down to the bottom of the list you will have 'Epilogue' below 'Ending'. Inside 'Epilogue' is 'Lost Secrets'.