This document discusses Rakuten's category system and efforts to improve it. It begins with an introduction to categories and an overview of how Rakuten's category data is used across 50 services. It then discusses the importance of ongoing measurement, modification, and rapid release of category data. The authors describe automating processes for measuring category performance from user data, modifying the category tree structure based on analysis, and releasing updates through standardized APIs. The goal is to continually optimize categories based on trends and make updates available in real-time and weekly to better serve users and merchants.