Managing money as a married DINK couple

Hi everyone,
My fiancé and I (both non-Japanese) are getting married soon, and we’ve been discussing how to manage our household finances once we’re married. I know “joint bank accounts” aren’t a thing here in Japan. So after a lot of discussing, we both decided that I’ll be handling the money, and he will get okozukai. This system works for both of us with very open communication all the way.

Here’s what we’re planning so far:

• He’ll give me his paycheck in cash each month, minus his allowance (for lunch money and small personal stuff).
• I’ll make him a family credit card tied to my Rakuten Gold Card so he can use it for other purchases.
• I’ll handle all the household payments, saving, and budgeting.
• We’re planning for a DINK lifestyle (maybe a pet in the future, but no kids). Also not planning to buy a house because we have plans to move/retire somewhere else down the line.
• We already have an emergency fund set aside for about 3–4 months of living expenses for both.

Questions:

1. Suppose every month he takes his paycheck out in cash and hands it to me, I deposit the money in my bank account, does it count as money liable to gift tax?
2. Since we also want to set up a NISA for him, can he use the rakuten family credit card (thats in his name, but linked to my bank account) to make contributions?
3. For anyone who’s in a similar setup, is there anything we should consider or adjust to make this more efficient or easier to manage long-term? Any other tips?

Thanks a lot in advance.