female employee of a brothel-massage parlor
Refers specifically to a woman working at a ヘルス (a type of sex business offering massage-like services). The term is a compound of ヘルス (from 'health', a euphemism for such establishments) and 嬢 (a suffix for young women in service roles).
He apparently often requests a specific girl at the brothel-massage parlor on weekends.
The working conditions of women employed as brothel-massage parlor workers are not widely known.
Compound of ヘルス (from English 'health', a euphemism for brothel-massage parlors) and 嬢 (じょう, 'young lady' or 'miss'). The exact historical derivation is uncertain, but the term is a modern coinage within the sex industry.