Japanese Emperor Akihito back in hospital
Japan's Emperor Akihito is reported to have undergone a procedure to drain fluid from his chest that had built up following heart surgery last month.
The 78-year-old was admitted to the Imperial Household Hospital, Kyodo news agency said.
Palace officials told Kyodo that a large amount of fluid had been removed without any problems.
They also revealed that the emperor had not recovered as well as expected from last month's bypass operation.
Emperor Akihito, who has suffered from poor health in recent months, underwent surgery in February at the University of Tokyo Hospital.
He left hospital on Sunday and was pictured walking on his own and bowing to doctors before getting in a car with his wife, Empress Michiko.
The head of state is reported to be keen to take part in the anniversary events of the 11 March earthquake and tsunami.
Although the emperor plays a largely ceremonial role, he is deeply respected by many Japanese.
He ascended the throne in 1989 following the death of his father, Emperor Hirohito.
Emperor Akihito also had surgery for prostate cancer in 2003 and suffered stress-related health issues in late 2008.
In 2009, the Imperial Household Agency said he would cut back on official duties such as speeches and meeting foreign dignitaries.