If you’re purchasing Detective Pikachu on Nintendo 3DS from Japan, you can expect to receive a pre-order bonus depending on where and how you purchase the game.
First up, all digital copies of Detective Pikachu will come with a special Home Theme. This is the only way to obtain the Home Theme. The design of this theme hasn’t been released yet.
Second, all pre-orders for the physical copy of Detective Pikachu in Japan will come with a special Detective Pikachu keyring which looks like this:
Last but not least, customers who pre-order Detective Pikachu from Pokemon Center or Pokemon Center Online will receive a special story book called “Detective Pikachu: Chapter 0 – Eevee’s Request”, which is a prologue to the events of what happened in Detective Pikachu before the detective meets Tim.