Anna Netrebko, Joseph Calleja and Jonas Kaufmann withdrew over concerns about conditions following the March 11 earthquake, tsunami and nuclear disaster, The New York Times reported.
The Met previously announced Olga Borodina wouldn't accompany the tour so she could rest her voice and that music director James Levine would not participate so he could recuperate from back problems.
The company of 350 musicians, choristers, dancers, stage crew members and principal singers arrived in Japan Monday ahead of performances in Nagoya and Tokyo, which begin Saturday. "Don Carlo," "La Boheme" and "Lucia di Lammermoor" will be performed.
Other company members expressed concern about the tour because of potential risks, but Met officials said experts and the U.S. State Department declared conditions safe and required all under union contracts to go on the tour.
"The majority of the company is very happy to be here," Peter Gelb, the Met's general manager, told the Times. "Stars are stars. They're different than company members. In the case of both Netrebko and Calleja, they were genuinely upset that they had to make these decisions."