Lopez signed a one-year, $1.1 million contract with the Yomiuri Giants of Japan's Nippon Professional Baseball in December, Francys Romero of MLB.com reports.
Lopez was released by the Mets on Thursday.
The Mets returned Lopez to Triple-A Syracuse on Thursday.
The Mets recalled Lopez from Triple-A Syracuse on Wednesday, Mike Puma of the New York Post reports.
The Mets returned Lopez to Triple-A Syracuse following Saturday's doubleheader with Atlanta.
Lopez was recalled by the Mets to serve as the 27th man for Saturday's doubleheader against Atlanta, Tim Healey of Newsday reports.