Can Japanese Cards be played if using an English based Deck?
No, although you can use foreign language cards from the TCG, OCG cards are not allowed.
From Konami's Yugioh FAQ, that lists several Official Tournament Stores

Q: Can I use foreign language cards in my Deck?
You can use foreign-language copies of legal-for-play cards printed for the TCG market, as long as you can show an official translation of the card, kept outside of your Deck and Deck box, when asked to do so by an opponent or tournament official.
Q: Can I use OCG cards in my Deck?
No. Cards printed for Asian markets are not legal for play in TCG tournaments.

There are several reasons for this, which make the cards identifiable in a regular TCG deck.