Erotic massage in Kolkata has very little in common with massage, or being erotic. The best sensual massage studios in Kolkata are usually located in or next to popular hotels.
Apart from that they’re just badly covered up brothels and don’t even pretend they know the first thing about massage. I heard good things about Glamour (https://glamour-kolkata.business.site/) at Block A, Lake Town district and Relaxsations (https://relexsations-massge-and-spa.business.site/) at BE - 54 Ground Floor, Bidhannagar. If they try and charge you more than $80 then it means you’re getting scammed.