선배 and 후배: the Korean school-year hierarchy that lasts for life

It’s the first week of the semester, and you’ve joined a university hiking club. You’re 20. You feel, frankly, quite grown-up.

Then the club does introductions, and the man next to you, who has a beard, a car and opinions about mortgage rates, stands up and says he’s 25 and just joined this semester. Everyone turns to you. Someone whispers, helpfully: “You joined in March. He joined in September. You’re his 선배.”

Your brain blue-screens. He’s five years older than you. He has a car. And he is now looking at you, very politely, waiting to see how you’d like to be addressed.

Welcome to 선배 and 후배 (seon-bae and hu-bae, usually written sunbae and hoobae in English): the Korean system that ranks people not by birthday but by when they walked through the door. It starts in school, peaks in university, and follows people into the office and beyond.

The short version: a 선배 is someone who joined your school, club, company or field before you; a 후배 is someone who joined after. Entry year usually matters more than age. Seniors are expected to look after juniors (often by buying meals), juniors are expected to greet, help and show respect, and the bond can last a lifetime. The system has a dark side (hazing, known as 군기), and younger Koreans are rapidly softening it. If you’re joining a Korean school or company, be polite to everyone, ask how this group does things, and let the seniors buy you lunch at least once.

Who’s the 선배? (Hint: not necessarily the oldest)

The Standard Korean Language Dictionary defines 선배 (先輩) as someone ahead of you in the same field, whether in position, age or learning, and 후배 (後輩) as someone who started in the same field later than you. The key words are the same field: you have 선배s in something, like your high school, department, club or company.

And inside that something, the clock usually starts on entry day. That’s what makes it different from the plain age order Koreans use everywhere else. Age decides who’s 형 or 언니 among friends. Entry decides who’s 선배 in a group you joined. Usually the two line up. The fun begins when they don’t.

The usual suspects that scramble the order:

재수생 (jae-su-saeng) and 삼수생. The dictionary defines a 재수생 as a student studying for another try at an entrance exam. Plenty of Korean students retake the university entrance exam once or twice, so a freshman class can include people a year or two older than their classmates, and older than some of their 선배s.
Military service. Many Korean men pause their studies for military service and come back as 복학생 (returning students), often a couple of years older than the people in their classes.
빠른 년생. People born in January or February who started school a year early under the old system, and who have been causing seating-chart arguments ever since. We cover that saga in our age article.

So the older 후배 and the younger 선배 are a fixture, and there’s no national rulebook for them. Students invent local ones.

“몇 학번이세요?”: the question that sorts a campus

At a Korean university, the magic word is 학번 (hak-beon), literally “study number”. Officially, the dictionary describes it as the student ID number a university assigns according to entry year and department. Socially, it’s shorthand for your entry year, and students introduce themselves with it: “24학번이에요” (“I’m a ’24”, meaning I entered in 2024).

Say / Mean: 몇 학번이세요? (myeot hak-beon-i-se-yo) says “What’s your student number?” It means “When did you enter, so I know whether to bow, relax or start calling you 선배?” The answer is just the last two digits of your entry year: “25학번이요.” Nobody wants your actual ID number. Please don’t recite all ten digits.

Once the 학번 is out, the department’s house rule kicks in, and departments differ:

학번제 (student-number system): entry year decides everything. A younger 선배 can speak casually to an older 후배, and the older 후배 uses polite speech and calls the younger one 선배(님).
나이제 (age system): age decides how people talk, whatever the entry year.
Mixed or free systems: polite speech for everyone at first, then switching by age once people get to know each other.

How much the rules vary is easy to underestimate. When Korea University’s student newspaper surveyed 61 departments on its main campus in 2014, it found that 57 were not actually running a strict 학번제. Many had switched to the age system, 18 used a hybrid, and a few had invented their own, such as one department that set a fixed point in the year before which everyone, of every year and age, spoke politely to everyone else. The holdouts included pre-med, where students linked it to medicine’s apprenticeship-style training.

So that bearded 25-year-old in your club? Under 학번제, you’re his 선배, full stop. Under 나이제, you call him 형 and he buys the drinks. In most real clubs today, you’ll both use polite speech for a while, feel awkward, and eventually settle on something that works. That awkward middle period is the most Korean part of the whole experience.

Life inside the system: 동아리, MT and the March of free lunches

The club (동아리)

The 동아리 (dong-a-ri), a student club, is where 선후배 culture is at its most concentrated. Clubs often count members by 기수 (gi-su), the “generation” you joined in, which is why someone can be your senior in the photography club and your junior in the department. Some students juggle three rankings at once, like a spy switching passports.

MT: membership training

Then there’s MT, pronounced em-ti and spelled 엠티 in Korean. The dictionary defines it as a gathering where members of a group train together to build friendship and harmony. In practice, “training” means a cheap rental lodge (펜션) outside the city, a mountain of ramyeon, drinking games, sleeping on a heated floor in rows like dumplings in a steamer, and one heartfelt 3 a.m. speech nobody remembers by breakfast. MT is where 선배s and 후배s really get to know each other, and, as we’ll see, it’s also where the worst of the old culture has tended to happen.

Meals: why March is expensive for seniors

Here’s the best part of being a 후배. In many Korean groups, seniors are expected to buy juniors meals, especially at the start of the year. Students even have a word for these lunch dates: 밥약 (bap-yak), short for 밥 약속, a “meal appointment”. A freshman can easily spend the first weeks of March being taken to lunch by a parade of 선배s, while the 선배s quietly watch their bank balance turn into what Korean slang calls a 텅장, an “empty account”.

And then there’s the ritual. You sit down. The 선배 opens the menu and says the line.

Say / Mean: 먹고 싶은 거 다 시켜. 내가 살게. (meok-go sip-eun geo da si-kyeo, nae-ga sal-ge) says “Order whatever you want. It’s on me.” It means “It’s on me.” The “whatever you want” part is real, but it comes with a little invisible asterisk. Experienced 후배s develop a sixth sense: never the most expensive thing, never the cheapest thing (that looks like pity), but the second-cheapest thing, ordered with enthusiasm. That’s nunchi with a side of kimchi.

If the 선배 orders the steak and insists you get it too, congratulations: you’re allowed.

What juniors owe in return

The free lunches aren’t charity. They’re one half of a deal. The other half, in a traditional group, looks something like this:

Greet first. A 후배 who walks past a 선배 without saying hello will be discussed. A quick “안녕하세요!” and a small bow cover most situations.
Help with the heavy lifting. Setting up events, carrying boxes for the club festival, booking the MT lodge, buying the snacks.
Mind the table. Pour for seniors and follow the choreography in our drinking etiquette guide.
Pay it forward. Next year you’re the 선배, and the freshmen are looking at you with hungry eyes.

In return, a good 선배 gives far more than lunch: advice on professors and courses, old exam papers and notes (students call these 족보, jok-bo, literally “family tree”), job-hunting tips, and later, sometimes, an introduction to their company. A mentoring system that runs on rice.

It doesn’t end at graduation

Most Koreans keep their 선배s and 후배s for life. A few places you’ll see the system after school:

At work. A new employee joins with an intake cohort, their 입사 동기 (ip-sa dong-gi), the people hired at the same time. 동기 often stay close for years, eating lunch together and tracking each other’s promotions with friendly suspicion. Everyone who joined earlier is a 회사 선배 (company senior), and in many Korean offices a new hire is paired with a senior who teaches them the job. Job titles officially run the office (see our business etiquette guide), but entry order is the quiet layer underneath. Two managers of the same rank may still act like 선배 and 후배 because one joined three years earlier.

In alumni networks. Korean has a word for ties formed through the school you went to: 학연 (hak-yeon). Alumni associations and “you’re from my school?” moments can open doors, and are also criticized as a closed network that favors insiders. Either way, if a Korean colleague discovers you attended the same school, even decades apart, expect an instant warmth upgrade. You are now, technically, family.

The dark side: 군기 and “똥군기”

Now for the part Koreans are not proud of.

In a hierarchy where juniors must obey and seniors are rarely questioned, some groups slid into 군기 (gun-gi), literally “military discipline”: seniors “straightening out” juniors with group punishments, verbal abuse, forced drinking and rules about how freshmen must greet, dress and speak. Students coined a sharper term for the pointless, humiliating version: 똥군기 (ttong-gun-gi), “crap discipline”. The word itself tells you what most young Koreans think of it.

This isn’t just campus folklore. Korean media have reported case after case:

2013, Busan. Police booked 18 students from a university sports department after seniors repeatedly forced juniors into 원산폭격, a punishing stress position with the head on the floor. One freshman collapsed, broke two teeth and later dropped out, according to Yonhap News.
2016, Seoul. Professors at a university sports department publicly apologized after seniors subjected freshmen to the same kind of punishments “in the name of hierarchy,” and the school opened a disciplinary hearing, MBC reported.
2018, Hongik University. Anonymous posts exposed hazing in a university cheer squad: memorization tests on seniors’ names, punishments outdoors in freezing weather, and forced drinking. The student council condemned it. In the same SBS report, a survey of 1,028 university students by a job portal found that 57.6% said they had experienced 갑질 (abuse of power) from a 선배, and 79.6% said military-style discipline should disappear “for any reason”. Police also ran a special reporting period for senior-junior violence that spring.

Many reported cases cluster in sports and performance groups, around orientation and MT season, when freshmen are newest and most eager to fit in. Universities have responded with human rights centers and reporting channels. Korean comment sections are many things, but on 똥군기 they tend to be united, and SBS summed up the mood in one subheading: “군대에서도 이렇게는 안 한다” (“They don’t even do this in the military”).

If you’re a foreign student, here’s the bottom line: respect is expected; abuse is not. No one can legitimately make you do punishments, drink, or accept insults because of your 학번. Saying no politely is fine, and your university’s human rights or counseling center exists for exactly this.

How the MZ generation is rewriting the rules

The good news is that the softer, kinder version of 선후배 culture is winning.

You can trace the shift in what students call each other. A 2007 survey by the job portal Incruit and research firm Embrain asked 2,134 graduates from the 1970s through the 2000s cohorts how they addressed seniors. Female students in the ’70s and ’80s most often called a male senior 형 (hyung); by the 2000s, 오빠 (oppa) was the top answer, and male students calling a female senior 누나 (noona) had climbed to 72%. Less formal, more sibling-like. (Those words get their own article.)

The next step goes further: many students now skip the ranking words altogether. In 2019, the Hankook Ilbo reported that students in group projects, study groups and clubs increasingly call each other by name, or add 씨 or 님, even between seniors and juniors in the same department. Some groups standardize on 씨 and use polite speech with everyone on purpose. Some students said it felt more equal; others worried it made relationships colder.

What you’ll often see on campus now:

Polite speech in both directions until people agree to drop it, instead of seniors talking down by default. (Who switches to casual speech, and when, is a whole art; see when it’s OK to speak banmal.)
“선배” instead of “선배님”, or names instead of either, especially in mixed-age groups.

Old habits survive, especially in medicine, sports and some traditional workplaces. But the default has shifted from “obey your seniors” to “be decent to each other, and let the 선배 buy lunch if they want to.”

What to do if you’re a foreign student or new employee

Before you know the house rules:

Use polite speech (존댓말) with everyone at first, including people who look younger than you. You can always relax later. Going the other way is harder.
Ask, kindly. “여기는 학번제예요, 나이제예요?” (“Is it the student-year system here, or the age system?”) is a perfectly normal question in a new club or department, and it shows you understand how things work.

When you’re the 후배:

Greet seniors first, with a smile and a small bow.
Accept the meal. Turning down a 선배’s offer to buy lunch can feel like refusing the relationship. Say “잘 먹겠습니다” (“I’ll eat well, thank you”) before eating and “잘 먹었습니다” after.
Order the second-cheapest thing, at least until you learn how generous this particular 선배 is.
Return the favor small. Buying the coffee after a 선배 buys lunch is a classic, graceful move.

When you’re the 선배 (yes, this may happen faster than you think):

Buy the occasional meal if you can. It doesn’t have to be fancy. A bowl of gukbap counts.
Don’t pull rank. Especially with an older 후배, polite speech and a little humility go a long way. The bearded 25-year-old from the hiking club will remember forever that you didn’t make it weird.

Common mistakes:

Assuming age settles it. In a 학번제 group, entry year may matter more.
Ordering the most expensive dish on a 선배’s tab. Legal, but memorable.
Never reciprocating. The relationship is a two-way street paved with lunches.
Putting up with hazing because “it’s culture.” It isn’t, and you can say no.

Done well, 선후배 culture is one of the warmest things about Korean life: people a year or two ahead who feed you, warn you about the hard professor, and turn up at your wedding fifteen years later. Somewhere right now, a freshman is ordering the second-cheapest item on the menu. Next March, they’ll be the one saying “내가 살게” and quietly checking their banking app.