noun
underground bank; clandestine bank
Refers to an illegal, unlicensed financial operation that provides banking services outside regulatory oversight, often associated with loan sharks or money laundering.
警察は地下銀行の摘発を進めている。
The police are cracking down on underground banks.
地下銀行を利用すると、高金利のローンを組まされる危険がある。
Using an underground bank carries the risk of being forced into high-interest loans.
Compound of 地下 (underground, clandestine) and 銀行 (bank). The term is a straightforward calque of the English 'underground bank'.