In Korea its kind of a loving term, so its used in cases where you're either on familial level with the person, or on extremely close terms with them (ie, bestfriend, good friend, and even lover). It's kind of like referring to someone as their second name in that aspect, so most people don't do it until a personal relationship is established. Though it can be used pretty loosely sometimes, it just depends on circumstance and the person
Tysm for explaining (๑•ㅂ•)و✧
It's also about their relationship on a professional level. I'm not sure since it's not as obvious in English, but the ML is a superior of MC, so MC would be using a respectful way of speaking. Like the above person said, "hyung" is used in a friendly term, in a casual setting. So it's NOT professional.
It's kinda like if your brother (or brother figure) works in the same company as you, ranked higher than you, and you call him bro in front of your boss.
Oh yes, also its a term used ONLY with men, and the younger of the two would be addressing the older of the two. Its not used between men of the same age, and its not used by females (they would instead use "Oppa". And yeah lol, like the other commenter mentioned its not a formal term so its not used in formal settings like the workplace where something more akin to "sunbae" or even "sunbae-nim" would be more appropriate, as in certain settings "Hyung" can be read as "bro" .
Wait, can someone educate me and tell me why it’s a big deal to call someone hyung?? (=・ω・=)