Japan has deported seven of 14 activists who sailed to disputed islands from Hong Kong, Japanese officials say.
The group left for Hong Kong from an airport in Okinawa, while the rest are expected to head back by boat.
The activists had sailed to islands known as Senkaku in Japan and Diaoyu in China on Wednesday.
The case has sparked a diplomatic row and a number of small protests outside Japanese diplomatic missions in China.
It is the first time non-Japanese nationals have landed on the islands - which are controlled by Japan - since 2004.
Seven activists left on a commercial flight from the southern island of Okinawa, while the others were flown to another island to take their boat with them, officials said.
Prime Minister Yoshihiko Noda had agreed to recommendations to send the group back, a top government spokesman said earlier.
Mr Noda, speaking ahead of a weekly cabinet meeting, said it was "extremely regrettable that they illegally smuggled themselves on to our island of Senkaku despite our repeated warnings not to".
Some opposition lawmakers, however, have criticised the move, saying that the activists should have faced criminal charges, says the BBC's Mariko Oi in Tokyo.
A group of 150 people are getting ready to sail from Japan's south-western island of Ishigaki to the disputed islands, reports the Agence-France Presse news agency.
The flotilla of 20 boats is expected to reach the islands on Saturday night.
China had repeatedly called for the activists' immediate release. Small groups of protesters also gathered outside Japanese diplomatic missions in Beijing, Shanghai and Hong Kong.
Both Japan and China lodged formal protests with each other over the incident, while the US urged the two nations to resolve the conflict peacefully.
Largely uninhabited, the islands are close to strategically important shipping lanes, offer rich fishing grounds and are thought to contain oil deposits. Taiwan also claims them.
Rows over the disputed islands have caused Sino-Japanese ties to freeze in the past.
In September 2010, relations plummeted after the arrest of a Chinese trawler captain near the islands.
The captain was accused of ramming two Japanese patrol vessels in the area, but Japan eventually dropped the charges against him.