Hal, Lucas has never publicly acknowledged YAMATO to the best of my knowledge, although there are many oblique similarities. Lucas was indeed in Japan, according to the late Robert Dunham (co-star of DOGORA), who set the young Lucas up with his contacts in the Japanese film industry, while racing cars in Southern California. Lucas was apparently shopping around for a Japanese studio to shoot the effects for "The Star Wars."

Interestingly, there are strong similarities between YAMATO's sequels and the STAR TREK movie series, starting with WRATH OF KHAN, which has many parallel elements seemingly borrowed from YAMATO: THE NEW VOYAGE and BE FOREVER YAMATO. Someone has written an complete listing of these parallels on the net...
August Ragone
Author, EIJI TSUBURAYA: MASTER OF MONSTERS
Coming this fall from Chronicle Books

Director, SHOCK IT TO ME! Classic Horror Film Festival
Oct. 5-7, 2007 • Castro Theatre • San Francisco