Japan’s banking crisis 1991

Banking crisis from 1991 - 2005
One of the main cause was the bursting of the asset proce bubble in the period of late 1980s to early 1990s.
Bank loans were overextended particularly in risky areas with inadequate supervision and regulation over banks during bubble period. (loan portfolios were concentrated in property related business)

What did stimulate crisis?

Factors
Banks were allowed to hold common stock on their balance sheet and had accumulated sizable unrealized capital gains, boosting their capital base. The decline of their capital base damaged banks ability to extend loans and take risks.