Overview

Amazon Japan has revised the search‑help page on Amazon.co.jp to spell out that a shopper’s own purchase and click history now feed into the ranking of search results they see. The update, posted on January 30 2026, does not alter the underlying algorithm but gives sellers a clearer view of the personalization signals that affect product discovery.

Key Points

• Help page refreshed — As of January 30 2026, the Amazon.co.jp search‑help article explicitly mentions that items a customer has bought or clicked on influence their search rankings.
• Personalization confirmed — The wording “customer preferences, e.g., items you previously purchased or clicked on” confirms that Amazon tailors results per shopper rather than delivering a single, uniform list.
• No algorithm change — Amazon states the edit is purely for transparency; the core ranking formula that weighs relevance, sales velocity, price, and fulfillment remains unchanged.
• Seller notification — Amazon announced the change through a Seller Central news post, indicating the company considers the disclosure material for sellers’ planning.
• Regulatory backdrop — The move aligns with growing scrutiny of e‑commerce platforms in Japan, where regulators are urging clearer explanations of automated decision‑making.
• Cross‑market relevance — Although the notice targets Japan, similar personalization mechanisms are known to operate on Amazon.com, Amazon.co.uk, and other regional sites.

How Personalized Search Works

1. Data capture — Amazon records every product a shopper clicks, adds to a cart, or purchases. For example, a user who buys a set of silicone baking mats will have that SKU logged in their preference profile.
2. Signal weighting — When the shopper later enters a keyword like “baking supplies,” the system adds a boost to listings that match the previously purchased category. In the same scenario, the silicone mat brand may appear higher than a competing brand the shopper has never interacted with.