This came across my Facebook feed - Rila Fukushima (who was great as Yukio in The Wolverine) will be playing Katana in Arrow season 3, replacing Devon Aoki who had to give up the role due to scheduling conflicts.

From ComicBook.com

You can also read the same thing on ComicBookMovie, GreenArrowTV, and Deadline, but they all tell the same basic story (and GA TV actually credits Deadline).