Here is a list of supported payment methods depending a mobile device.

[Google Play]
1. Credit or debit cards that allows foreign purchases
2. Mobile phone billing (Data charges)
3. Google Play gift cards
4. Payco Points
5. KaKao Pay

[App Store]
1. Credit or debit cards that allows foreign purchases
2. Mobile phone billing (SKT, KT)
3. KaKao Pay

* In-app purchases are processed through the App Store or Google Play.
Depending on the type of your card, you can be charged with DCC (Dynamic Currency Conversion) fee.