For years, the Japanese have fetishized small things for their convenience, easiness of storage, and ability to be sold at higher prices even if they're technically not quite as good. Since 1845 when the Everything Smaller Now! Act was passed by Japanese government - consisting of a lone Ninja randomly placing bills, amendments, and even riders onto village doors, holding them in place by stabbing them with a bloody knife then disappearing into the shadows - it has been federal law that all things in Japan must be made at least 10% smaller than anything in the United States.
Most difficult to shrink were the actual Japanese themselves. Once standing over 15 feet tall with legs like the trunks of great oaks, they can now conveniently fold up and be placed inside anyone's pocket.
Due to a few clauses, though, there are some things that remain bigger in Japan than they do in the United States.
One of the things Japanese hold most dear is their tentacle monster rape porn. While it may seem obvious why tentacles would be bigger in Japan than in the US, the issue was actually hotly debated. Those for the miniaturization argued that if tentacles were made smaller, then one schoolgirl could be raped by upwards of dozens or even hundreds of tentacles simultaneously, instead of the current maximum of about five.
A compromise was reached when it was agreed that the tentacles would remain the same size, but the actual tentacle monster would shrink. Some say this was an overall defeat of Tentacle Miniaturists, though, as the smaller bodies just made the tentacles appear larger by comparison.
edit Bottles of Hot Sauce
Japan's national slogan is "Furu ike ya kawazu tobikomu mizu no oto" which in English translates to "We are not pussies." The Japanese are known to use bottles of hot sauce - some as large as propane tanks - in a single bowl of noodles for two reasons: 1) they are not pussies, 2) the hot sauce, which eats away at the insides, is what actually caused the Japanese to become smaller. In only 160 years since the Japanese first began eating large amounts of hot sauce to shrink themselves, they've managed to decrease their size nearly 75%.
edit Weird Cartoony Things
Japan's third largest export, behind Useless Techno-Shit You Don't Need, and Helpful Techno-Shit You Actually Do Need, is Weird Cartoony Things. Weird Cartoony Things need to be an appropriate size for weirdness to properly ferment. Small things are, it has been proven, not that weird.
edit Television Graphics
It is unknown to most why Japanese television stations must use graphics that take up nearly half the screen, though there are those who speculate why. Most consider a simple concept or relativity. Television sets could not shrink along with the Japanese and their other, more often replaced household items (it is estimated some Japanese refresh cell phones every three hours, each one only microns smaller than the last). To remedy this, the images on the screen instead became increasingly larger, causing the television to appear smaller relative to the image on the screen. Another theory is that it's something to do with their small slitty eyes.