4,000 (1,000,000) = 4,000,000,000 JPY = 40,000,000 USD.
If you get taxed 25% Federal Income and 4% State Income Tax (CO for example), then you'll bring home $ 28,400,000.
If you spend $60,000 per year for living cost, then it'll be good for 473 years.
Let's assume that you're buying a house worth of $1.4M. That shortens things up to 450 years.
Yep, even if you buy new car every 5 year, you'll not need to worry about money. Just don't get scammed.