Pokemon Sword and Shield fans have found out that the game is hiding a surprise secret which adds more mystery to the hit Nintendo Switch game. Pokemon Sword and Shield has been out for a month now, and it has been a huge hit for the House of Mario. Game Freak’s latest offering managed to sell over six million units digitally and physically during its opening weekend.

It has made it the fastest selling Nintendo Switch game to date, beating the record previously set by Super Smash Bros Ultimate.

In the US alone Pokemon Sword and Shield managed to sell two million units during its first weekend on sale.

It remains to be seen how much Pokemon Sword and Shield sells by the end of the year, but it’s likely to be a huge number.

And the Pokemon Sword and Shield fanbase have discovered a very interesting detail about the Switch game.

As revealed in a post by GameRant, Pocket Monster trainers have stumbled upon something curious in the Galar region.

They have spotted an interesting detail about Sword and Shield gym leader Allister.

One of the most striking things about Allister is the mask that he wears, with fans trying to understand the importance of it.

And Reddit user Aekis may have cracked what is the significance of the mask.

The Redditor said that the mask could potentially be the forehead of the newly introduced Galarian Corsola.

Allister’s trainer card says he keeps a hundred masks with similar designs to hide his identity.

He also claims to have been able to see deceased Ghost-type Pokemon following an accident that took place when he was aged just four.

Here is what his trainer card says: “He is a young, mysterious Trainer who has taken on the mantle of Gym Leader at a very young age.

“He has never been known to remove his mask in public.

“In fact, he has at least one hundred masks of the same design, just to keep spares handy should his mask fall off for some reason.

“He claims to have developed the ability to see deceased Ghost-type Pokemon after an accident he had when he was four years old, but the truth is still a mystery.”

Could this mask somehow be tied into the accident Allister had when he was younger?

The idea of Allister wearing a mask that has been made out of a Pokemon is certainly an interesting – if macabre – one.

And if Game Freak confirms it then it surely adds an extra dimension to this enigmatic character.

Hopefully more backstory on Allister will be revealed in the upcoming Pokemon anime series that is based on the Galar region.

• Stay tuned to Express.co.uk for more Nintendo Switch news