Major construction company Aoki Corp. filed for court protection Thursday, unable to seek further aid from its creditors. The collapse is a foretaste of more to come, as banks hurry to clear their books of bad debts.

Just 2 1/2 years ago, Aoki's 26 creditors agreed to waive 204.9 billion yen in liabilities. In return, they received a restructuring plan that would get the contractor back on its feet over a 20-year period.

That comfortable pace belonged to an era when cross-held shares knit banks and companies tightly together, and when banks could afford to wink at slow profits because land and prices were supposed to go up again.