The actress will have a major recurring role as Katana, who will be seen in flashback sequences as a mentor to Oliver Queen (Stephen Amell). The character is a deadly martial arts expert who is a "critical influence" to Oliver on his journey towards becoming Arrow. It isn't immediately clear how many episodes she will appear in during Season 3.
In the DC Comics, Tatsu Yamashiro's Katana sword also had supernatural abilities, capturing the souls of all the enemies she vanquished. It isn't known if this aspect of her character will be transferred over to the TV series. Katana also had ties to the Birds of Prey in the comic books, a group which was teased in Season 2 with the return of Huntress (Jessica De Gouw) and the introduction of Black Canary (Caity Lotz).
Earlier this month, we reported that Arrow will introduce four new characters in Season 3, two of which will be featured in Oliver's flashbacks, although it doesn't seem that these characters have been cast yet.
Devon Aoki's other credits include 2 Fast 2 Furious, Death of a Dynasty, DOA: Dead or Alive, War and Mutant Chronicles.