Ken Watanabe, whose "Godzilla" role is one of several appearances in Hollywood films, acknowledged pressure was high for how the film may be received in Japan.
"It might be a challenge for Japanese to accept this movie," he said after posing with a figure of Godzilla on the red carpet.
He said some scenes show the wreckage of a giant tsunami, evoking painful memories of the March 2011 disaster in northeastern Japan, which killed nearly 19,000 people and set off the worst nuclear catastrophe since Chernobyl.
"I have a special feeling for this film because of the disaster," Watanabe said.
Edwards' 3-D Godzilla, complete with glistening scales, spikes down its back and a terrifying roar, pays homage to the original, tracing the theme of the threat of radiation, following America's atomic attacks on Japan in World War II.
Although Godzilla has grown to be one of Japan's most iconic exports, along with sushi and geisha, its status in mainstream entertainment has waned here.
Toho Co., the creators of Godzilla movies since the first one in 1954, stopped making them after the 28th in a series in 2004.
Officials say times have changed and an actor thrashing about in a rubber suit, smashing miniature models of buildings, just doesn't cut it anymore.
Watanabe said the film's late opening in Japan was because of technical reasons about summer vacations coming later, and denied it was intentional to avoid jinxing it by having it possibly fail in the land of Godzilla's birth.
But he laughed and shook his head when asked whether the best was being saved for last.
Hard-core Godzilla fans think nothing can live up to the charm and pathos of the original, and scoff at computer graphics and other modern filmmaking technology.
Akira Takarada, who played the young diver in the first "Godzilla" and appeared in many sequels, said he burst into tears when he watched the new "Godzilla" in the U.S., and the crowd began stomping on the floor, and then gave Godzilla a standing ovation when it finally appeared about an hour into the movie.
"A giant hero they had been waiting for had arrived," he said with emotion in his voice.