Japan Dev

Looking around the internet, it seems Shift Inc. is paying around 4.5-5.0 (full range: 3.8-7.8) million JPY / year total comp.
This is about 40k-45k USD/year. It's somewhat better than what engineers would get on a black companies and local consulting companies and perhaps on par with some of the traditional blue chip companies.

But this doesn't come anywhere close to what a software engineer can earn on the highest paying companies here, like Google or Indeed (levels.fyi pegs Google L4 as earning 14-23 million JPY per year, though the dataset is a little bit small).

Even the large local IT-focused companies are competing for talent: Yahoo, Line, Rakuten, Works Applications, Mercari etc. will all pay up to 11m-13m for non-manager software engineers (even though they won't necessarily pay much higher for entry-level engineers). Many well-funded startups are also paying 7m-10m salaries to their engineers.

The pay gaps between different companies in the very same city (Tokyo) for the same position can be quite high. You can read more about it here:
https://japan-dev.com/blog/software-developer-salaries-in-japan-the-ultimate-guide

In short, if Shift Inc. is paying around 5m for their engineers, it might help them fight high turnover, but it won't be enough to bring the best engineers. There are companies which are both more well-known and stable and are still paying higher salaries.

I think the options you have listed are pretty accurate. If you are a working for a large multi-national then getting an internal transfer to the Japan office is probably the best way to move to Japan.

As for companies in Japan, there is a wide range. From very old fashioned businesses where programming is seen as simple grunt work to modern development shop that keep up with industry best practices. If you don't speak Japanese you will limit your options, but filtering for English speaking workplaces will probably leave you with a smaller number of better companies.

Start off by taking a look at the English speaking expat focused job sites [1][2].

If you have a university degree and can get hired by a company in Japan the visa situation is very straightforward. No lotteries or waiting lists, just a few forms.

You would be right in saying that salaries tend to be lower. This article[3] from JapanDev is a good starting point. Cost of living is also lower, depending on your lifestyle. Inflation is starting to catch up with Japan so it's not clear what things will be like in the future.

[1] https://japan-dev.com/

[2] https://www.tokyodev.com/

[3] https://japan-dev.com/blog/software-developer-salaries-in-japan-the-ultimate-guide

I got my current employment being introduced by someone inside. I found my previous company via job website, here are two that I find most helpful:

https://japan-dev.com/jobs

https://www.tokyodev.com/

Obtaining residence: my current visa is (quite long):
"Engineer/Specialist in Humanities/ Int'l Services" (技術・人文知識・国際業務)
I got this visa sponsored by my first company, which is the most common thing for foreigners. Mine is 5 years, some are just a year long. It all depends on the company and how they file your paperwork.

I don't have permanent residency. I could switch over to spousal visa, but since I still have a lot of time left with my visa, I'm not going to bother the bureaucracy. Also, getting residency isn't as easy; it's like a point system here: how long you've been working, if you went to school in Japan, JLPT (Japanese Language Proficiency Test), etc.

Guarantor is only necessary for renting apartments (from my experience).

That's so weird. Employers have always paid for employees' commuting expenses here in Japan [0]. It's not even mandated by law and there's a legal limit of 150k yen / month, roughly $1000 though most companies limit it to 25k (~$200). Still it's enough that commuting by bullet train is a thing [1].

Even part timers get reimbursed.

[0]: https://japan-dev.com/blog/employee-benefits-in-japan

[1]: https://www.reddit.com/r/japan/comments/y1nurn/places_outside_of_tokyo_where_i_can_commute_to/