Like a monumental battle between formidable rival kaiju, Criterion and Arrow have released competitive Blu-ray sets devoted to Japanese monster movies. Criterion’s Godzilla: The Showa-Era Films 1954-1975 and Arrow’s Gamera: The Complete Collection offer eight disks of monster mayhem in packages too big to fit on my shelves. Binging more than two-dozen of these movies dragged my brain blissfully back to childhood.