I worked in Japan for ~7 years. I don't think I can relate with any of this, for starters I think not speaking Japanese relatively fluently would completely shape your experience from the get go.

Granted, this was a long time ago and even seeing non-Japanese around in Tokyo was rare, unlike now. But in the office environment let alone in tech, I doubt you can really make it work without not just speaking Japanese, but being considerably adapted to their culture. I think the chances of the dev just moving to Japan to work in tech and be anything other than a total outcast are poor. Which is ok if you plan to just do a year or two maybe. Even the author himself first got well acquainted with the language and culture then moved into development. And even so, this is hardly for but a select few to just fit into this lifestyle.

For North Americans or Europeans, the intersection of people who can make it work and are also incentivised to make it work looks infinitesimally small to me, esp. if you can opt for jobs in the industry in America or even Europe. It's a totally different story for someone from say South Korea or Taiwan, or to a lesser extent other Asian countries. For starters, coming in as a junior dev in Japan or as a translator won't be a massive pay downgrade for them. For South Koreans and Taiwanese the culture will be a lot more familiar, although there will of course still be some friction. So imagine coming in as mid-manager or higher, wow it sounds like quite the experiment to me knowing the place well. CEO with capital, maybe. But good luck with that.