The newly-released Pokémon Brilliant Diamond and Shining Pearl include a teasing new addition fans believe is a hint to next year's Pokémon Legends: Arceus.
A fresh book has been discovered in Diamond and Pearl's Canalave Library - a location found a fair way into the game - with all-new text that describes a mysterious Pokémon legend.
Brilliant Diamond and Shining Pearl are pretty straightforward remakes - so the inclusion of something not in the originals stands out.
You can find the book for yourself by heading to the correct bookcase shown in the video above, at the 00:51 mark. (Credit to our resident Pokémon expert Chris Tapsell for recording that.)
"This book is titled 'The Sea's Legend'," the game tells you. "It's a text that was only recently discovered, and its ancient letters were decoded." This sounds a lot like a nod to the book's recent addition in the Diamond and Pearl remakes.
Selecting "Yes" to "Would you like to read it?" brings up the following tale:
"Once upon a time in the East Sea, there was a Pokémon known as the prince. A brave human asking Pokémon living in the sea to let them see the prince.
"Mantyke, Buizel, and a Qwilfish with huge spikes acknowledged the human's bravery and joined them. Together, they set off in a boat over the sunset-streaked sea, sailing through the ocean gate stretched over the waves.
"News of this reached the ears of the prince, who went to meet the brave little party at the Seaside Hollow."
Pokémon Legends: Arceus is set hundreds of years before the events of Diamond and Pearl, in a historical version of the same geographic region. It would make sense if this "recently discovered" legend related to Legends: Arceus, and perhaps a mission in that game.
Fans think the Pokémon "prince" refers to the Mythical creature Manaphy, the last Pokémon in Diamond and Pearl's Pokédex. Manaphy starred in the franchise's ninth movie, which was named Pokémon Ranger and the Temple of the Sea, or in Japan, The Pokémon Ranger and The Prince of the Sea.
"A Qwilfish with huge spikes" could refer to a new form of Qwilfish native to Arceus' ancient Hisui region or a fresh evolution entirely. Already, we've seen announcements of existing Pokémon gaining new forms and evolutions - and there are rumours of others still under-wraps.
Seaside Hollow is, intriguingly, a new location not found in any existing Pokémon game.
Fans think this all points to an encounter with the Mythical Manaphy at some point in Arceus, which would be one of only a few times it has appeared in the series. Perhaps you need the three named Pokémon in your party to make Manaphy appear? It's something to keep in mind when Arceus arrives in January next year.