The short answer
Compare Japan and Korea marketplaces by SKU contribution after seller-funded discounts, platform and settlement fees, product cost, fulfilment, storage, returns, and local support. Set allowable advertising cost from what remains, not from gross sales.
Marketplace fees are not one comparable percentage. Qoo10, Rakuten, and Amazon Japan separate selling, plan, promotion, payment, fulfilment, storage, or return charges in different ways. Coupang and NAVER Smart Store also use different selling, payment, traffic-source, solution, and fulfilment rules. Use public pages to identify the fee structure, then confirm current values in the contract and seller account.
SKU contribution equals customer-paid revenue minus seller-funded discounts, platform and settlement charges, product cost, cross-border and domestic fulfilment, storage, seller-borne duties, returns, refunds, and local-language support. Allowable advertising cost is the contribution before ads minus the required profit buffer.
Separate platform, SKU, and promotion rows. Record standard-price orders, discounted orders, first and repeat purchases, and post-return orders independently. Attribute coupons and points to the party that funds them; gross merchandise value and dashboard ROAS are not substitutes for settled contribution.
Reconcile the model with monthly settlement statements, fulfilment invoices, refunds, and actual support workload. Expand only the SKUs that remain above the stop threshold after returns, inventory holding, and local operations.
The Fit Call is a 30-minute pre-contract mutual-fit check with no research, calculation, strategy, or deliverable. Channel economics, allowable media spend, and a 90-day priority plan are analyzed only after a paid Market Diagnostic agreement: ¥300K–¥500K over 2–4 weeks. Managed Engagement is ¥800K–¥1.5M per month when execution is approved.