A sakana ichiba (fish market) at Shibuya station is our favorite Tokyo battleground. Close to closing time, customers hover around the refrigerator cases, scouting out the sushi and sashimi assortments--especially the packages of maguro, mutsu, and more. Then, at about 7:45, the man with the marker does the "makete" (discounting) action, slashing prices on fish that must fly off the shelves. We jostle for position, reaching for the best boxes of uni and chunks of......