Social Democratic Party leader Mizuho Fukushima said she has no regrets about leaving the ruling coalition and will only consider returning if the Democratic Party of Japan rules out the Henoko coast as the relocation site for U.S. Marine Corps Air Station Futenma in Okinawa.

"I have zero" regrets about leaving, Fukushima said. "I personally experienced that there were many things we could do as a part of the government and the ruling bloc. . . . But if we had signed (the agreement to move the base to Henoko), the public would have lost their trust in the SDP."

The SDP left at the end of May after Fukushima was booted out as consumer affairs minister for refusing to endorse the Japanese-U.S. agreement to move the contentious air station from crowded Ginowan to Henoko, a district farther north on Okinawa Island and part of Camp Schwab.