The actions of a Japanese lawmaker set off a storm of protests on the Internet, with some critics calling on him to resign from parliament.
Taro Yamamoto gave Emperor Akihito a letter expressing fear about the health impact of the Fukushima nuclear disaster, breaking a taboo by trying to involve the emperor in politics.
Yamamoto explained his actions to a group of lawmakers on Friday.
SOUNDBITE: TARO YAMAMOTO SAYING (Japanese):
"The fact that I myself handed over a letter to the Emperor is just because I wanted him to know my personal feelings about the current situation on the ground. In eastern Japan there are children coming down with many health problems and there are people who are working in radioactive conditions who are just being ignored - this is the reality. I just wanted to convey that to him."
Three reactors had meltdowns at the Fukushima Daiichi plant after Japan's 2011 earthquake and tsunami.
About 150,000 people were evacuated from ar