A Diet member who handed a letter to Emperor Akihito at an autumn garden party last week said Tuesday he will not step down, despite harsh criticism that his act was a grievous breach of protocol.
Taro Yamamoto, an independent House of Councillors member, did offer an apology at a news conference and said, "I regret that what I did has troubled the emperor." He also said he was not sufficiently aware of the consequences of his action.
Yamamoto, known for his antinuclear activities, last Thursday handed the emperor a letter detailing the current working environment at the disaster-hit Fukushima Daiichi power plant.
Yamamoto has denied using the emperor for political purposes.
The nation's Constitution defines the emperor as the "symbol" of Japan and stipulates "he shall not have powers related to government."
On Tuesday, Yamamoto told Mitsuhide Iwaki, chairman of the upper house's Standing Committee on Rules and Administration, that he intends to stay on as a lawmaker. The committee is discussing whether to discipline him.
The Imperial Household Agency criticized Yamamoto the same day, saying doing what he did on such an occasion was "inappropriate."
"It was a matter to be decided in line with common sense," Shinichiro Yamamoto, vice grand steward at the agency, said at a press conference. The garden party should be an occasion "to thank people from various sectors for their services."
The letter was not read by the emperor and has been retained by a member of the agency, according to the senior official.