All the good Japanese engineers are already working for a big company and they are not likely going to change to a smaller one. For Japanese workers, security is usually the priority number one.
So yes, if you have a degree in STEM, it's really not that hard to emigrate to Japan. To know Japanese would open a lot of doors, but it is not mandatory if you have a good CV. Also, anybody can get a decent level of Japanese with two years of study.
On the other hand, you can probably make much more money in California, or even in London than in Japan. And also, the work-life balance in Japan is practically inexistent. When you sign a job contract with a Japanese company, they assume that you are giving your entire life to them. You are allowed to go home to sleep and bathe, but just because they are kind with you.
So yes, Tokyo has interesting things, but is not as amazing as we thought it would be. Also, there are no punks... everybody obeys like robots.