Hello! I’m @mikichin from the Mercari Engineering Office.
On November 13th, we will be holding “mercari GEARS 2025,” the Mercari Group’s tech conference!
After seven years since our last “Mercari Tech Conf 2018,” we are finally returning to an offline event.
The theme of the event is “Mercari’s Engineering Today.”
We will introduce how engineering within the Mercari Group has evolved since 2018 from the perspectives of technology, organization, and culture—covering not only this year’s company-wide theme “AI-Native” but also the broader changes.
There will be no online streaming, so please come to the venue and see and hear it for yourself!!
This time in addition to presentations, we will also have a poster session.
During the poster session, presenters will be standing in front of their posters, so you can ask questions and exchange information. Please feel free to stop by.
*Please note that presenters will not always be standing in front of their posters. There will be times when they are not present.
This article introduces all the poster sessions you can only see at the venue!
Please check here for the session introduction article.
PASSION Stage URL：https://engineering.mercari.com/en/blog/entry/20251008-mercarigears2025-passion-stage/
GROW Stage URL：https://engineering.mercari.com/en/blog/entry/20251009-mercarigears2025-grow-stage/
MECHANISM Stage URL：https://engineering.mercari.com/en/blog/entry/20251010-mercarigears2025-mechanism-stage/
If you haven’t registered yet, take a look and you will find sessions that will interest you. Please register here.
The Full Picture and Future Vision of AI-Native Incident Management at Mercari Group
The popularization of LLM technology is significantly changing the nature of incident response and management.
Mercari Group has decided to evolve its practices for incident management, which is often complex and cumbersome, to become AI-Native.
We will introduce IBIS, a tool that we have already implemented, as well as related mechanisms and other cases of AI utilization.
By incorporating AI, we can expect not only a reduction in MTTR, but also lower burden and stress for responders, decreased costs, and improved service reliability.
However, there are still areas where humans should be involved. In this presentation, we will share Mercari Group’s current initiatives and future outlook.
The 3A’s: Simple Steps For Clean Unit Tests
Software moves fast, and every new feature or fix carries the risk of breaking something that was working before. Without proper safeguards, even small mistakes can slip into production and affect thousands of users.
That’s why unit tests are so important. They don’t just check your code—they protect your product, your users, and your team’s confidence. Writing good unit tests ensures stability, reliability, and peace of mind when making changes.
But how do we keep our tests simple, clean, and effective?
One proven approach is following the 3A’s framework: Arrange, Act, and Assert. These three steps make it easy to structure unit tests that are clear, maintainable, and trustworthy.
Autonomous Support – Leveraging AI Bots for Scalable and Intelligent Operational Assistance
We’re building an AI-assisted, autonomous support system that turns noisy Slack inquiries into fast, reliable answers and standardized tickets. Today, engineers lose time to reactive, repetitive questions and emoji-driven triage across uneven workflows; teams spend >10–20% of time on inquiries. Our bot meets users where they are (Slack), triages the right JIRA/GitHub tickets, searches a shared knowledge base (docs, past tickets, Slack, source code), and proposes an answer. If the issue needs a human, the bot routes and hands off; if not, it closes the loop and learns. The result: faster response and resolution, fewer interrupts, and measurable impact through metrics like Autonomous Resolution Rate, Escalation Rate, Engineer Hours Saved, CSAT, and Knowledge Gaps identified—while reusing existing platform tooling to move quickly.
Toward a Global Identity Platform
Mercari launched its crossborder business in 2019. At that time, users outside Japan had to search for and purchase items through proxy pages with limited functionality. To deliver a better shopping experience for global users, Mercari has since expanded its system and begun rolling out services in other countries. A key requirement for this expansion was the introduction of a global account. In this presentation, we will share what we have accomplished so far and outline our plans to further extend the Identity Platform to support users across multiple countries.
Practical Knowledge Gained from Assisting Non-Engineer Organizations in Their AI-Native Transformation
The transformation of non-engineer organizations to become AI-Native is a process that requires the support of engineers.
In this session, I will talk about my experience as an engineer in that process, including:
(1) Examples of customizing input/output formats to achieve desired results through AI utilization
(2) Lessons learned about lifecycle management from an incident where an AI workflow suddenly stopped
(3) Methods for safely deploying AI-generated apps using GAS
These are just a few examples of the practical knowledge I will share for guiding AI utilization from prototype to actual application.
From Cluttered to Clear: Improving the Web Accessibility Design for Screen Reader Users in E-commerce With Generative AI
Blind and low vision users often face significant barriers when navigating online shopping websites using screen readers. Complex layouts, unclear content hierarchies, and visually driven designs create a frustrating and inefficient browsing experience, particularly on unfamiliar platforms. While prior accessibility tools focus on isolated elements such as product descriptions or image alt text, they often fall short of addressing the structural and navigational challenges screen reader users encounter across entire webpages. In this work, we explore how Generative AI (GenAI) can be leveraged to improve the accessibility of shopping websites by automatically restructuring their HTML content. We conducted a three-phase study: formative interviews with screen reader users, system development of a GenAI-powered browser extension, and user evaluation through both automated audits and real-world testing. Our tool dynamically reorganizes web content to better align with screen reader navigation patterns. Results from user studies with blind and low vision participants show that the GenAI-generated pages significantly improve navigation efficiency, content clarity, and overall usability. Participants highlighted benefits such as more logical section order and reduced browsing fatigue. Our findings demonstrate the potential of GenAI to support comprehensive, user-centered accessibility improvements directly within the structure of existing websites.
Quantum Internet: Working to Realize a Safe, Secure, and Sustainable Online Society
Mercari’s research and development organization, R4D, is conducting research on quantum information and communication technologies to prepare Mercari for the "quantum era" approaching in the imminent future. This poster presents an overview of the research and development on the quantum internet that the R4D quantum team is pursuing in collaboration with research institutions in Japan.
Erasure-tolerance protocol for the surface codes on neutral atom quantum computers
A neutral atom array with optical tweezers is a promising candidate for a quantum computer, thanks to its good properties. Some major barriers to overcome are non-Pauli errors, erasure errors, and leakage errors. Conventional work has revealed that leakage error is convertible to erasure error. A remaining problem is that such (converted) erasure errors continuously happen and accumulate. In this study, we evaluate the effects on planar code by circuit-based Monte Carlo simulation which has depolarizing errors and erasure errors and propose a new protocol to tolerate erasures which uses online code deformation to transfer the logical qubit from traps in which erasure errors accumulated to other refreshed traps.
The Power of Reuse: Building a Bridge to a Sustainable Future
Reuse—passing on items that are no longer need to a new owner instead of discarding them after a single use—is one of the most accessible and practical choices we as consumers can make to help build a sustainable society. In this presentation, we show the impact of reuse through concrete data, demonstrating how it contributes to the realization of a sustainable society by extending the lifespan of products.
Through this talk, we hope to inspire people to embrace reuse as a default option in their everyday lives when considering letting go of items and acquiring new ones and to discover for themselves the “hidden value” that items still hold through this practice.
Exploring Human-AI Collaborative Writing of Product Descriptions on Online Flea Market Apps from the Sellers’ and Buyers’ Perspectives
Online marketplace apps have become a popular way for individuals to sell secondhand items directly to other individuals, particularly in Japan. The listing process requires sellers to upload photos and write product descriptions for potential buyers to view. In recent years, the application of human-AI collaboration has attracted attention, especially in reducing the burden on sellers through item description generation powered by large language models (LLMs).
This study examines not only how LLM-based assistance affects the seller experience and listing prices, but also how collaboratively written item descriptions influence buyers’ subjective impressions and preferences regarding a product’s appeal. The findings contribute to a deeper understanding of the potential impact of LLM-based tools on online secondhand markets and provide insights into design considerations and future research directions for human-AI collaborative writing systems tailored to marketplace apps.
Utilizing AI in Ad Screening for Mercari Ads
Mercari Ads, which launched in September 2024, initially involved manual review of ads submitted by advertisers.
In pursuit of a more efficient review process, we built an ad review system utilizing AI to reduce operational costs and enable us to review a larger number of ad materials.
In this session, we will share details about this system.
BFF Maintenance Challenges and Solution Approach with gRPC Federation
In BFF development within a microservices architecture, maintenance costs tend to increase due to type conversions across multiple services and the complexity of dependency management. This presentation introduces a case study where these challenges were addressed by adopting gRPC Federation and automatically generating BFFs through definitions written in a DSL for Protocol Buffers, thereby achieving a significant reduction in maintenance costs. We will also share our efforts leveraging AI in supporting DSL authoring.
Engineering Office is a Hub, connecting Engineering together
The Engineering Office is the hub that connects and communicates with all parts of our engineering organization. It allows the group to align and focus across various areas and tasks, from shared onboarding to project support and engineering information.
This presentation will share some parts of our projects, where we use automation, AI, and continuous service lifecycles to respond quickly to business needs and help maintain Mercari’s unique engineering culture.
Overview of Mercari’s Recommendation System
Recommendations are made in various places on Mercari, such as the home page and item detail pages, and technologies tailored to their respective characteristics are applied behind the scenes.
In this presentation, we will share an overview of the various types of recommendations used on Mercari and the technologies behind them. Let’s exchange information through discussion!
Apply for “mercari GEARS 2025” here.
Event Details
Event Date and Time：
November 13th (Thu), 2025 11:00-18:00
Overview：
mercari GEARS 2025 is a tech event that invites you to experience the culture and technical challenges of Mercari’s Engineering Organization first-hand.
More than a series of information-sharing sessions, the event is a place for engineers to meet, share their experiences, and create new opportunities through interaction.
Held on November 13th, the event caters to software engineers working at tech companies and people interested in Mercari Group’s technologies.
Participation fee: Free
Venue：TODA HALL & CONFERENCE TOKYO
How to Participate: Please register on this page.
【Official Site】
For any additional information about this event, we will announce it on @MercariGears as it becomes available. If you’re interested, please follow us.
