Hired by Iron Man and Captain America to investigate the Japanese underworld on behalf of the Avengers in New Avengers (1st series) #11-13. Officially joined the team in #31.
Echo became Ronin in New Avengers (1st series) #10. Ronin was a mystery character who appeared in several early promotional images for Brian Michael Bendis's New Avengers series. "Ronin" was intended as a disguise identity for Matt Murdock, who Bendis had risen to popularity writing in Daredevil. However, when Ronin's identity slipped out early thanks to an interview with USA Today, Bendis revisited the concept and made Maya Lopez into Ronin instead.
Echo was killed by Count Nefaria in Moon Knight (6th series) #9. After Secret Wars, she was inexplicably alive again as of Daredevil (5th series) Annual #1.