noun, noun or participle which takes 'suru', intransitive verb, noun which may take the genitive case particle 'no'
A covering for the face, often to hide identity. Can be used as a noun, with する to mean 'wear a mask/disguise', or as a no-adjective.
犯人は覆面をかぶっていた。
The criminal was wearing a mask.
覆面
A masked man suddenly appeared.
noun-modifying (irregular), noun
anonymous; unmarked; incognito
Used prenominally to describe something done anonymously or without revealing identity, such as 覆面調査 (mystery shopping) or 覆面作家 (anonymous author).
覆面作家の正体は誰も知らない。
No one knows the true identity of the anonymous author.
覆面調査員が店のサービスをチェックした。
A mystery shopper checked the store's service.