What is a Rakuten genre ID?
A Rakuten genre ID is the number that identifies one genre, one position in the hierarchy Rakuten Ichiba uses to organize products. Rakuten’s Genre Search API returns genre names and their structure by Genre ID, with genreId=0 as the root, so every product’s place in the mall can be written as a path of genre IDs. Which genre should your product be in? The one where a shopper who wants this exact item would naturally look, checked against where close competitors place similar items; the step-by-step method is in the diagnosis guide.
Rakuten Ichiba in plain language
Rakuten Ichiba is an online mall in which independent shops sell under one roof. Each shop lists its own items, and Rakuten organizes the mall so that shoppers can search by keyword, browse by category and filter results. The company describes its wider ecosystem on its group pages; for a seller, the practical point is that your product does not stand alone. It sits in a structure that you did not design.
What a genre is
Genres are the hierarchy Rakuten uses to organize items. Rakuten’s Genre Search API describes them as genre names and their structure, retrieved by Genre ID, with the root represented by genreId=0. A genre has a parent and may have children, so the path from the top to the final genre tells you where a product lives. Every item in Ichiba is placed somewhere in that structure.
The structure can change. Rakuten may add, rename, merge or move genres. That is why a product that was well placed last year can drift, and why an audit after a structure change is a sensible habit.
What a tag is
Tags describe attributes of an item, such as its use, material, size or audience, and help it match the way shoppers narrow their searches. Merchants set tags while registering items in Rakuten Merchant Server (RMS); the screens and the names of the fields are defined by Rakuten and can change, so confirm them in your own RMS account. Tags work together with the genre: the genre says what kind of thing it is, the tags say what kind of that thing it is.
How placement can affect discoverability
Shoppers reach products through a keyword search, a genre page, a filter, a ranking or an advertisement. Rakuten’s Item Search API shows that results can be limited by genre, and its Item Ranking API describes sales data divided by genre, gender and age group, with up to 1,000 ranks. These documents show that genre is a first-class part of how Rakuten organizes data. They do not publish the full ranking formula, and anyone who claims to know exact weights is guessing.
The safe reading is modest: a sensible genre and accurate tags put the product in front of the people who are looking for it, and a poor placement can make it harder to meet them.
What is usually not the cause
Many visibility problems are blamed on placement when something else changed. Price, stock, delivery terms, images, reviews, campaign timing and demand are all common alternatives. Paid promotion also changes what shoppers see: Rakuten Promotion Platform (RPP), Rakuten’s click-based advertising service for merchants, can add or remove exposure independent of your genre. Newsletters sent with R-Mail, Rakuten’s mail marketing tool for merchants, can shift traffic in the same way. Check these first.
Why honest placement wins
It is tempting to place a product in a busier genre or to add popular tags that do not describe it. That is misleading to shoppers, may breach Rakuten’s rules, and brings visits that do not buy. A truthful, well-chosen placement is easier to defend, easier to measure and easier to maintain.
What to do with this
Start with the diagnosis guide, then follow the optimization workflow. If you also sell on a catalog-first marketplace, read why Rakuten search differs from Amazon search. The book overview and the complete book page show how the 200 prompts apply these ideas to your own shop.
Sources and verification
Last reviewed 4 October 2026. Rakuten changes its genre structure, search features and Rakuten Merchant Server (RMS) tools from time to time. What follows describes the pages as published by Rakuten at the time of writing, which may change. Always rely on the current wording in your own RMS account and on the official pages below before you act.
Educational guide only. Not legal, tax or financial advice. Independent of, and not affiliated with or endorsed by, Rakuten. No ranking, traffic or sales result is guaranteed.