OK, this should be fun. You've got lots of amazing authors ahead of you. David Mitchell has always acknowledged that he is a big fan of Murakami so the fact that you like both of them makes a lot of sense.
So, authors and books to suggest:
PAUL AUSTER. Most fans of Murakami are also fans, to some extent, of this American writer. Slightly surreal and odd with a lot of focus on the narrator. I would start with The New York Trilogy.
RAYMOND CARVER. Murakami's literary influences are all American and this was probably the most important influence on his work. Carver only ever wrote short stories but all his collections are worth checking out.
PAUL LaFARGE. Relatively unknown American writer whose Artist Of The Missing novel owes a debt to Murakami.
RICHARD GWYN. Only one novel from this Welsh writer - The Colour Of A Dog Running Away - but it is a lot of fun and worth a read.
TOM McCARTHY. His debut novel Remainder is just out and is remarkable, you'd probably like it if you like Murakami.
RYU MURAKAMI. No relation and not as good as Haruki but if you like a bit of Japanese fiction then he is worth a try.
GRACE PALEY. Murakami translates her stuff into Japanese, she is pretty good.
Hope that helps, enjoy reading!