Why did Japan’s economy completely blow up in the 90s? What actually caused the bubble?

I’ve been reading about Japan’s economic boom in the 1980s and how everything seemed to be going really well, especially in places like Tokyo where property and stock prices were rising fast. But then in the early 1990s, everything suddenly collapsed and the economy struggled for years.
I understand that after the Plaza Accord, the Bank of Japan lowered interest rates, which encouraged borrowing and investment. Still, I’m not sure how that turned into such a massive bubble.
Why did prices rise so much, why did banks keep lending, and what exactly caused the crash? Was it mostly policy mistakes, or did people simply become too optimistic about the market?