The short answer
Choose Rakuten or Amazon Japan by account eligibility, store operations, fulfilment, returns, Japanese support, data access, and SKU contribution—not a generic brand-versus-convenience rule. FBA does not replace import or compliance ownership.
There is no universal winner between Rakuten and Amazon Japan. Compare category and account eligibility, Japan selling and import responsibility, platform costs, inventory, fulfilment, returns, Japanese support, data access, and operator capacity for the same SKU set.
Rakuten's official documentation describes multiple store plans, monthly charges, system, payment, and points-related costs, and RMS store-operation tools. Store screening and product restrictions also apply, so storefront preference alone does not establish channel fit.
Amazon Japan documents selling plans, category referral fees, seller fulfilment, and FBA. FBA handles storage, order processing, delivery, customer service, and returns after inventory is received; it does not remove the seller's import, labelling, category, or inbound-inventory responsibilities.
Choose the first channel only after a small SKU set passes account approval, listing review, post-return contribution for standard and promotional orders, inventory-turn, Japanese-support, and settlement-data gates. Start both only when ownership and budget can support two distinct operations.
The Fit Call is a 30-minute pre-contract mutual-fit check with no channel research, calculation, strategy, or deliverable. First-channel selection, allowable media spend, and a 90-day validation plan are analyzed after a paid Market Diagnostic agreement: ¥300K–¥500K over 2–4 weeks. Managed Engagement is ¥800K–¥1.5M per month after execution approval.