We’ve come to the second-to-last installment in the Showa era Gamera series, and the last "real” installment, as the next film will be a clip movie.  Unfortunately, while Gamera vs. Monster X was a revitalizing breath of fresh air in the series, Gamera vs. Zigra is the biggest bore since Destroy All Planets.  Just watch the Mystery Science Theater 3000 version of the flick.  It’s the only way.