Japanese Emperor Akihito, who received a heart surgery last month, underwent a checkup Friday before deciding whether to attend a quake memorial ceremony on Sunday, according to Imperial Household Agency sources.

The 78-year-old emperor had a chest X-ray at the Imperial Household Hospital following the removal Wednesday of fluid that had accumulated in his chest after his heart bypass surgery.

On Sunday, Prime Minister Yoshihiko Noda is scheduled to attend an official ceremony to mourn the victims, which will be held at the National Theater in Tokyo.

The great earthquake measuring 9.0 on the Richter scale, which hit northeast Japan at 2:46 p.m. local time on March 11, 2011, and ensuing tsunami killed over 15,000 people and also triggered the nuclear crisis at the Fukushima No. 1 nuclear power plant.