OH! sry I meant the usage of "sister" rather than "noona" in an english dialogue sounds wrong because it takes on a different meaning (like blood relation rather than an honorific for someone not necessarily blood related to you)
Hahaha, I'm also asian, so we do use similar honorifics as "noona" to someone who's not a blood related sister :P
Ohh that's interesting. Cause for my culture whether blood related or not, it's the same term. But ya, maybe it's best for translations, just change it to their own names in English or like what you said, just use "noona" since that makes more sense than "sister". Probably cause in English that could also mean a nun
Why does he call her sister