Actually, there is a huge difference between a concubine and a mistress.Just to clear up the raw discussion:
妾 (mekake) literally means concubine/mistress. Neko comes from a super traditional family background, so using "concubine" fits her character and explains why Akebi reacts the way she does on the page. Downplaying it misses the point of the lore.
As for お別れをみせる (o-wakare wo miseru), sure, miseru is "to show", but page transitions exist for a reason. Having page 15 end with "I guess our only choice is to break up..." creates the intended dramatic setup that immediately resolves on page 16 when she mentions the drama club. Translating it as a past event ("show people we broke up") just makes the dialogue sound awkward and creates weird plot confusion that isn't actually there in the Japanese.
We localize for narrative flow and how characters actually talk, not line-by-line dictionary dumps. Enjoy whichever release you like!
A concubine has a socially recognized semi-marital status as a secondary partner, while a mistress is an extramarital partner in a clandestine relationship.
To put it simply:
- concubine = not cheating
- mistress = cheating
A traditional family will not discriminate against a concubine's child, it's part the traditional norm (monogamy has been the legal norm in Japan only since the Civil Code of 1947), unlike one born of an affair.