ふくめん覆面fukumen
1.

A covering made of fabric or material that conceals the face, often used to maintain anonymity or create a sense of mystery.

2.

The act of performing actions or roles without revealing one's true identity, commonly associated with anonymity or pseudonymity in various contexts, such as criticism or law enforcement.

3.

A specific cloth or material used to cover the mouth during rituals or ceremonies to prevent breathing or contamination, particularly in the context of offerings to deities or serving esteemed guests.

Example:

覆面をした男達が旅客を襲って金を奪った。

ふくめん覆面fukumenパトカpatoka-
1.

A police vehicle designed to blend in with regular civilian cars, often lacking the distinguishing markings and colors typical of police cars, used primarily for undercover operations.

2.

A covert law enforcement car that appears unremarkable to the public, allowing officers to monitor traffic and conduct investigations discreetly without drawing attention.

3.

An official vehicle used by police that resembles ordinary automobiles, enabling surveillance and apprehension of suspects without revealing its authority until necessary.

ふくめんごうとう覆面強盗fukumengoutou
1.

A person who commits robbery while concealing their identity with a mask or disguise, often to evade capture.

2.

An individual involved in theft who uses a face-covering to hide their features, typically during a surprise attack.