Starting on Saturday, December 4th, 2021, if you purchase one of the packaged versions of Pokémon Brilliant Diamond or Shining Pearl or a download card for those games at the same time as you buy a download card for Pokémon LEGENDS Arceus at participating stores nationwide in Japan, you will receive a special gift box with a Pokémon design! When opened, the gift box will hold both the packaged software and the download card. Be sure to check it out!

Participating Stores:

• AEON / AEON Style / AEON Super Center (Game stores)
• EDION Group (Game dealer)
• Joshin
• Game TSUTAYA Stores Nationwide
• Bic Camera/Sofmap (Game stores)
• furu1 Used Book Market/Book Square
• Yamada Holdings (game dealers)
• Yodobashi Camera

Source: https://www.pokemon.co.jp/info/2021/12/211203_cm01.html