Once you finish the main storyline of 's, there are still plenty of things to do, including using Briar's Book for a secret meeting. Briar will give this book after the capture of the newest legendary Pokémon, Tarapagos.
After Tarapagos is captured and the group heads out of é's Area Zero, credits will begin to roll. Once the credits finish rolling, you will be notified that Briar is looking for you in one of the Blueberry Academy classrooms, where, after a short conversation, she will hand over her book about Area Zero that will be added to your inventory.
Once the book is in hand, open up the map and switch to the Kitakami region, where the occurred. If the Crystal Pool fly point has been unlocked, fast-travel there. If not, use the closest travel point to the top of the mountain and head there. Once at the top, you will come across a large pond with crystals underneath it. Ensure that Tarapagos is in your party before going any further; otherwise, this will not work.
Go to the point where a piece of land cuts into the pond, where you first encounter a Milotic in 's DLC. Once there, toss out Tarapagos and give the game a minute to trigger the cutscene. If it doesn't immediately trigger, try moving around until it does. A thick mist will break out across the area if it has begun, and a mysterious figure will appear. Whether the stranger is Professor Sada or Turo varies depending on which version of the game, or, you are playing.
Let the cutscene play out and continue the conversation accordingly. Once the conversation ends, the Professor will ask you to exchange Briar's book for their own. Unfortunately, though the illusion of choice exists, there isn't a choice. If you decline to hand it over, they will insist until
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