#Japan #Tokyo #E-Commerce #Gaprise #LCP

September 2025 E-commerce Site Speed Rankings

In the ever-evolving digital landscape, Gaprise, a Tokyo-based SaaS company specializing in digital business support, has recently published the latest e-commerce site speed rankings for Japan as of September 2025. This ranking assesses the performance of 272 e-commerce sites based on their loading speeds. The data gathered offers valuable insights for retailers looking to optimize their online platforms.

Survey Overview

The evaluation period for this research took place in September 2025. Focused on sites with a monthly traffic of at least 100,000, we used the official dataset from Google's Chrome User Experience Report. The analysis compared the Largest Contentful Paint (LCP)—a key metric measuring loading performance—across these websites while being accessed on mobile devices with 4G connections.

Understanding LCP

LCP stands for Largest Contentful Paint and is one of Google’s Core Web Vitals. It measures the time it takes for the main content (typically the largest image or headline text) to be displayed after a user opens a page. A lower LCP score indicates quicker visual rendering, enhancing user experience. According to Google, an LCP display time within 2.5 seconds signifies good performance, while over 4 seconds is considered poor. Notably, Renault has demonstrated that performance improvements can push LCP down to under 1 second.

Notable Rankings and Insights

The standout feature of the current rankings is that all top 10 sites have achieved an LCP of 1.2 seconds or lower. Leading this group are popular online stores like Murauchi.com, AmiAmi Online Shop, and BAYCREW’S STORE, which have all broken the 1-second barrier, indicating top-notch loading speeds.

Across the 272 evaluated sites, approximately 75.7%—206 sites—achieved an LCP within the good performance range of 2.5 seconds or less. This finding suggests a growing awareness among e-commerce platforms regarding the significance of site speed and a commitment to active enhancement.

Renowned companies such as Belluna and Daytona International have implemented the website speed optimization tool 'Speed Kit', successfully reducing their LCP below the critical threshold of 2.5 seconds. Belluna has achieved remarkable results, with a 7.2% increase in conversion rates (CVR) and a 33% improvement in overall site speed within just three months of Speed Kit's implementation. This reflects a successful balance of user experience enhancement and tangible business impact.

Core Web Vitals: Introducing INP

This month's Best 5 sites showed no change in rankings, highlighting their stable and continuous high interaction performance. The INP (Interaction to Next Paint) is a crucial metric as it gauges how responsive a webpage is to user interactions. Analyzing INP alongside LCP offers a comprehensive view of site performance, underscoring the importance of continuous improvement not just in LCP but also in INP.

Efforts by these companies to improve their performance scores include:

• - Optimizing JavaScript execution
• - Streamlining event handlers
• - Enhancing rendering performance

Further Insights and Resources

For additional data on the remaining 270 sites and more detailed improvement case studies, please visit our media platform, MarTechLab.

About Gaprise

According to Gartner Japan, the total IT expenditure in Japan is projected to increase to approximately 28.5 trillion yen in 2023, with predictions of surpassing 30 trillion yen by 2025. As of 2022, the SaaS market represented only about 4% of this total at 1.1 trillion yen, indicating significant growth potential.

Since its establishment, Gaprise has focused on identifying and proposing innovative technologies from around the world. Collaborations with both large publicly traded companies such as monday.com and startups raise its profile within the competitive SaaS market. With the dissolution of Google Optimize, Gaprise remains committed to offering diverse tools for A/B testing and site speed improvement from February 2024, adapting to meet client needs.

Our services encompass various areas such as market analysis, online customer acquisition, optimizing in-site user experience, project management, AI technologies, and more, all geared toward accelerating business growth.

Company Name: Gaprise Inc.
Founded: January 27, 2005
CEO: Akira Yoshiyuki
Capital: 200 million yen
Location: 2-2-1 KANDA SQUARE WeWork 11F, Kanda Nishikicho, Chiyoda-ku, Tokyo
Website: https://www.gaprise.com/