Neighbour is loud every single night — what do you actually do?

Go to the operator. That is what they are for, and it will not make it worse — this is the specific thing goshiwon management exists to handle.

Why going direct rarely works: you knocked once and it lasted two days, which is the normal outcome. A neighbour who complies for 48 hours after a face-to-face knock will drift back, and repeated direct confrontation in a building where you share a wall is where things actually get worse.

Why the operator is the right route:

- Quiet is a rule of the building, not a favour you are asking. Goshiwon were built for exam students and the noise expectation is stricter than in normal housing. Every operator has had this conversation dozens of times.
- Complaints are normally passed on without naming you. The operator says "someone has complained about noise at night" — that is standard and it is why this works.
- If it continues, the operator can and does ask people to leave. They have more leverage than you do and they care, because a noisy resident loses them several quiet ones.

How to raise it so it gets acted on:

1. Note the times over two or three nights. "Videos on speaker, 23:30 to 02:00, Monday to Wednesday" is actionable. "He's noisy" is not.
2. Tell the operator in person if you can, and follow up on KakaoTalk so there is a record.
3. Say plainly that you have class at 9am. That framing lands in a building full of students.
4. If nothing changes after a week, go back once. Persistence matters and operators respond to a second visit.

In the meantime, and these genuinely work: a fan or white noise app masks speaker noise far better than earplugs block it, and foam earplugs on top of that handle most of the rest.

And the real backstop: you are on monthly terms with a month's notice. If the building will not manage its own residents, that is information about the building, and leaving costs you nothing but the move.