Reality check: Freelancing in Japan with family – real costs?

I'm a senior graphic designer (9.5 years experience at a major US company) planning to move to Japan with my wife (Japanese citizen) and two kids (ages 9 and 6). We would be moving to the countryside of Gunma. 4LDK renovated house is ~¥120,000/mo ($800).

I'm planning to freelance doing marketing and presentation design for US companies remotely, but I haven't freelanced full-time before. Life in California is break-even on a high salary, and I'm hoping we can have a better standard of living in Japan.

Looking for reality checks on:

1) National health insurance costs for family of 4?

  • What did you actually pay in Year 1 with low/no freelance income?
  • How much does it increase as income grows?

2) Real monthly living costs for family of 4 in Gunma?

  • Rent, food, utilities, transportation, school costs – everything
  • What do you actually spend?

3) Freelancing timeline – how long until viable income?

  • How long did it take you to build sustainable monthly income?
  • What's realistic to expect in Year 1?
  • For comparison: How hard is it to find a full-time remote position with a US company?

4) Kids adjusting to Japanese schools?

  • The kids speak conversational Japanese and have been studying kanji. They'll have to catch up to peers but have a strong foundation.
  • How long did adaptation take for your kids? Any unexpected challenges?

I have good runway saved up, but trying to set realistic expectations before making this jump. Honest feedback appreciated – positive or negative.

Thanks in advance!

by TheHandsomeSasquatch