Bill Nighy bought every Pokemon book in existence to research his role for 'Pokemon: Detective Pikachu'.
The 69-year-old actor did a lot of reading about the pocket monsters video game and trading card phenomenon after landing a part in the upcoming live action movie in which he stars with Ryan Reynolds, Justice Smith and Suki Waterhouse.
Nighy was aware of the Nintendo games when he was approached about the project but he took it upon himself to buy up the various monster guides and books, including the Pokedex encyclopedia which gives the information and stats for every creature in the Pokemon universe.
In an interview with Collider, he said: "You could have written what I know about Pokemon on the end of a pin. I knew about the cards and I knew it has become an app, but I didn't know it's now the second biggest company in the world after Apple.
"I didn't know after they released the trailer recently on Twitter, I think - and I don't have any social media - 280 million people watched it. You just realise this is a very serious outfit and now I kind of love the whole thing.
"I have come to know quite a lot about Pokemon because I immediately bought every Pokemon book there is and the masterwork is the Pokedex, which gives you everything you need to know."
The 'Love Actually' star is pleased that he did read up on the Pokemon universe - which kicked off in 1996 with the release of 'Pokemon Red' and 'Pokemon Green' on handheld console the Nintendo Game Boy - and he now considers himself to be not only a fan but a bit of an expert.
He said: "There is an enormous amount to know because the level of detail and depth they've gone into about every Pokemon, about the Pokemon trainer and the geography, which island they come from and which of the seven superpowers they have.
"They all have three at least and it's quite tremendous. I met the man who drew them all - there were 820 altogether and I think it's gloriously daft and wonderful."