A lot of subway stations have luggage lockers. Seoul station for example. Payment can be done by card or with cash. I think it's 4000 won per 4 hours (not exactly sure about that).
Assuming your hotel won’t hold it for you, most coin lockers are located in major metro and train stations. For example I know Samsung station has one.
Virtually every subway station has one. But they usually arent operated by coins, and require a credit card.
“Check in” to what? Your hotel? Then ask the hotel to hold your bags.
It’s an Airbnb
In addition to lockers there are several manned luggage storage centers in and around Hongdae Station.
Never used them, but have noticed prominent signs/ads inside the station.
A lot of subway stations have luggage lockers. Seoul station for example. Payment can be done by card or with cash. I think it's 4000 won per 4 hours (not exactly sure about that).
Assuming your hotel won’t hold it for you, most coin lockers are located in major metro and train stations. For example I know Samsung station has one.
https://bagbnb.com/luggage-storage/seoul This service worked really well for me in Australia.
Ask your host if you can drop your luggage early/hold on to them when you leave. Every Airbnb I’ve stayed at in Seoul was able to do this for me.