> Japan isn't particularly culturally friendly to startups.
It's quite the contrary.
Japan, or at least its entertainment industry and pop culture, is full of entire franchises started by minor, independent artists and coders, aka doujins [0]:
> amateur self-published works, including manga, novels, fan guides, art collections, music and video games. ... Of the $1.65 billion of the Otaku industry in 2007, doujin sales made up 48% ($792 million).
You forgot to mention it's mostly because doujin is pornographic in nature. That's why it's so big. Now if you were to classify pornography in a separate category, well the numbers would look much lower.
Vocaloid culture, Touhou, Cave Story.. immediately come to mind as doujin that became a hit in the world at large and aren't pornographic in nature. There are many that Western audiences never even know of.
Many visual novels too, though they may include sex, aren't really focused on porn, just like the many Hollywood movies that contain sex scenes are not "porn."
Conversely, you could say the US has no real equivalent to the doujin scene.
WHY is even a physical Silicon Valley still necessary?
One could argue that the doujin way is a better launchpad for a wide variety of ideas than VC-funded startups:
People, especially young people including many females, create something from the comfort of their bedrooms, without any pressure (like many software/game devs of the 1980s), other people enjoy and even improve their products, and if they get popular enough then big companies may turn them into proper franchises.
Why doesn't the US foster that kind of environment more? Why does everything have to be a company with millions of dollars? In fact, most of the Western internet is actually hostile to young artists and developers..
It's quite the contrary.
Japan, or at least its entertainment industry and pop culture, is full of entire franchises started by minor, independent artists and coders, aka doujins [0]:
> amateur self-published works, including manga, novels, fan guides, art collections, music and video games. ... Of the $1.65 billion of the Otaku industry in 2007, doujin sales made up 48% ($792 million).
[0] https://en.wikipedia.org/wiki/Dōjin