I was reading something for work the other day that actually made me laugh (it's been a long week). The passage was going along as normal as can be expected when a new character was introduced: "Tanaka-san's wife (a concubine in nature) appeared at the restaurant..." A concubine in nature?! I immediately contacted the person who had translated it to confirm whether
a) The wife was being slandered for her sexual promiscuousness
b) The wife wasn't actually married to Tanaka-san
c) The wife was an actual kept woman
蓄妾 【ちくしょう】 (n,vs) keeping a mistress (concubine)
This one had me looking twice because the first character contains a kanji used with words having to do with cattle but I'm not sure if there is any connection there.
籠の鳥; 篭の鳥 【かごのとり】 (exp) (1) caged bird; (2) person whose freedom has been restricted (esp. a prostitute, mistress, concubine, etc.)
I had seen the term "caged birds" being used before to refer to courtesans in the Yoshiwara pleasure quarters but had forgotten about it until today. I like the image it conjures (not that of indentured slaves but I think the term is fitting).
In cultures with concubinage systems, concubines were basically common-law wives (with the exception of those who were actually slaves) and a few more dictionary searches confirmed this. When I looked up concubine in English, it gave two definitions:
1. Common-law wife
2. Wives other than lawfully wedded wife
Then when I looked up the Japanese for common-law (内縁, naien) which is probably what the translator did, it came up with both common-law and then further down it translated it as concubine (when used in the context of a concubinage system). Still, I'm not sure why the translator thought concubine would be more fitting but at least I got a laugh out of it and have the phrase "a concubine in nature" to add to my arsenal.