Suffice to say it's can use as Mr or Ms for English tongue as well instead of just can be mean as big/elder brother/sister, it would be a lot of sense in most Asian countries to say that way since there's similarity calling those words
Well the raw just hit chap7 so far, but maybe it will happen like.. idk over Chap35+ or something? Otherwise this is just wasting my time reading this series if there's none :c