The short answer
Payment, the final conversion step, differs by market. Japan leans on non-card methods like convenience-store payment and cash-on-delivery, while Korea leans on easy-pay — so localizing checkout reduces drop-off.
Beyond credit cards, Japan widely uses convenience-store (konbini) payment, cash-on-delivery, and carrier billing. Supporting cards only causes meaningful conversion loss.
Korea has rapidly adopted easy-pay such as Naver Pay, Kakao Pay, and Toss. Shoppers expect a few-tap mobile checkout.
Checkout localization is more than translation — it includes payment methods, currency, and disclosure wording. Offering market-appropriate payment options alone can improve conversion.