"I've been here for nine days, eight nights. I have not had a lot to eat or drink," he told AFP on Thursday at Narita's Terminal 1.
"I have a Chinese passport that is valid for three more years. I have a valid visa for Japan, but I do not want to stay in Japan. I want to go home."
London-based human rights group Amnesty International lists Feng Zhenghu as a prominent activist who has been jailed in the past.
He told AFP, speaking in Chinese, that he had tried to go back to China eight times since he came to Japan in April for a break, having served 41 days in detention at the hands of Shanghai authorities earlier this year.
He said Japan, where many of his family members live, is a safe and comfortable country, but that he now wanted to exercise his right to return to his home country.
"Four times I was turned back by Shanghai authorities at the Pudong airport. They did not let me into the country," he said, adding that he had first tried to go home in June.
"The other four times, Japanese airlines refused to allow me onto the aeroplane. I strongly protest these actions. According to the UN (charter), no nation has the right to refuse the citizenship of its nation.
"Chinese law also stipulates this. What they have done to me is a violation of UN regulations and China's own law."
Despite his ordeal, Feng looked well-kempt and clean shaven, but speaking in broken Japanese, he said, "My stomach has become small."
He was also displaying a Chinese-language message -- which said in part "China Shanghai ... abducted ... difficulty returning home" -- written in black marker pen on a white tank-top that he had draped over his small suitcase.
He told AFP that his lawyer, Mo Shaoping, had sued Chinese local authorities in a Shanghai court for refusing him entry.
Feng said he had also launched legal action in a Japanese court over the airlines' refusal to allow him onto a China-bound plane earlier despite the fact he had a valid passport.
"I haven't seen a case like this before," said a spokesman for the Japanese immigration service at Narita.
"We have tried to convince him to enter Japan, but it is his choice to stay there," he told AFP.
The spokesman added that, until Feng seeks to re-enter Japan, his case is not the responsibility of the immigration service.
"Without such a request, the immigration authority cannot do anything about this," the spokesman said.
Feng said he had bought eight tickets back to China and had not been refunded for any of them.
He started his latest attempt to return to China after visiting the United States in October, the month China held its National Day celebrations.
Overseas-based activists in an unsigned statement said supporters planned to fly into Narita airport on a "Tokyo Airlift" to bring Feng food and offer their support, and called on others to do the same.
The supporters, in a message that gave no sign of affiliation to a political or rights group, said Feng first entered Japan on April 1.
Another rights activist, named as Yang Kuanxing, was quoted as saying: "Feng's situation is the movie 'The Terminal', with starvation. However, Feng’s personal remake of Spielberg’s blockbuster lacks the same humour and romance."
Steven Spielberg's 2004 film "The Terminal" tells that story of a man trapped in New York's JFK airport when he is denied entry to the United States but cannot return home because a revolution there has invalidated his passport.
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