She has plenty of history with Japan and Japanese characters. Shes been in an asiain body for quiet some time since all the Kwannon stuff. Psylocke was also essentialy trained by the hand, the hand destoryed her british body, she killed Matsu'o Tsurayaba to spare him from Wolverine endlessy torturing him after what he did to Mariko.
Psylocke is a freaking ninja when it comes down to it. With her connections to The Hand, having her in a film that takes place in Japan would be a great choice for introducing her,its an easier way to explain her complicated backstory. Most of her backstory connections come from there and I doubt we will ever see The Hand in another X film. I also highly doubt her start from the Captain Britain family side of things will ever be shown on the screen. Dont think Fox owns the Braddock family besides Betsy. They would need to simplify her regardless of what X Men film she does show up in.
