Tokyo: A Japanese television report says Emperor Akihito will have heart bypass surgery.
Public broadcaster NHK says the 78-year-old Akihito will have the surgery on February 18.
The Imperial Household Agency says the emperor returned on Sunday from the hospital, where he received tests, but did not elaborate. The agency official in charge of commenting to the media was not immediately available.
Akihito was admitted to University of Tokyo Hospital for tests on Saturday.
He has had various health problems in recent years, including pneumonia and prostate cancer. He has cut back on public duties but appears relatively healthy.