The Ultimate Spoiler from Gouto, Raidou's Mentor

The ultimate spoiler about who the real culprit is will be added to the Detective Journal.
It is not recommended to view this if you haven't completed the main game yet...

*This DLC can be used after the Detective Journal is unlocked in the game.
*For further information on details added to the Detective Journal, please see "How to Use Downloadable Content" in the in-game Detective Journal.

More details on the official game page of A Special Briefing ...