Thank you for coming!


Mercari’s mission is to “Create value in a global marketplace where anyone can buy and sell.”

Go Bold
All for One
Be Professional

Every member at Mercari embodies the above core values, and strives to improve our services.

The Mercari Tech Conference will showcase the accomplishments of the distinguished engineers who work diligently towards making the company mission a reality.

The theme for this inaugural conference is “Next”–touching on the past, present and future of Mercari’s technological endeavors.

Simultaneous Japanese-to-English interpretation will be available at the event, so Japanese language ability is not required to participate!

*Photos from Mercari Day, held on January 20th, 2017


Doors Open
In the 4 years since it was first released, the Mercari marketplace application has been downloaded over 75 million times globally and has grown to a point where it now handles over 10 billion yen in transactions each month. Our speakers will reflect on Mercari’s development, offering a developer’s perspective on the company’s different technical strategies, team structures, and development processes. They will also give us an introduction to the technical challenges they plan to tackle from here on.
Mercari Server-Side Deployment: Present and Future
Much has already been said about Mercari’s server-side deployment on our engineering blog, but this presentation will approach the issue from a different perspective, discussing the background and systems that have brought us to our current situation. The presentation will also offer a glimpse into the future of deployment here at Mercari.
Golang Package Composition for Web Application: The Case of Mercari Kauru
This presentation will be all about the Mercari Kauru app (released in spring of this year), discussing everything from Golang package composition to how to use its interface.
US Mercari iOS App Architecture and Dependency Injection
We introduced a new architecture for the US version of the Mercari app in order to better tailor it to the American market. This presentation will offer a simple explanation of some of the simpler dependency injection mechanisms we built in at this stage.
High-Performance Android: Rebirth of our US App
Team DevelopmentAndroidGlobal
Mercari unveiled a newly renovated US app tailored to the American market back in June of this year. This presentation will discuss the work that went on behind the scenes to make this release possible, focusing on the give-and-take inside an Android team with members located on opposite sides of the Pacific.
Has Image Recognition Technology Surpassed Human Abilities?
Machine LearningFeature
With the dramatic development of deep learning, we have reached an era where technology has partially surpassed human accuracy in image recognition. This presentation will discuss Mercari’s use of image recognition technology in identifying items listed on the marketplace, as well as our plans for future development.
Building a Team of Engineers in the UK
Team BuildingGlobal
Closing Remarks
- 20:30
After Party


Sotaro Karasawa
VP of Engineering
Sotaro started the engineering group Nequal LLC in late 2007. After finishing graduate school at Chuo University in 2010, he joined Gree. In February 2011 he started Crocos, Inc.–a company that offers social marketing tools, and became the CTO. In August 2012, the company was sold to Yahoo. After the acquisition, he continued to lead the business growth of Crocos, Inc. as a Yahoo subsidiary, and also worked in social and business development at Yahoo. He joined Mercari in May 2015, as executive and CTO, unifying their various technological departments. In April 2017, he became Mercari’s VP of Engineering.
Tatsuya Tsuruoka
Head of Engineering, Souzoh
As the Head of Engineering, Tatsuya oversees the management of the Souzoh development groups. From 2005, he worked at Unoh Inc. where he developed a photo sharing service, and afterwards started his second company. In 2013, he received an offer from Mercari’s CEO Shintaro Yamada, and began to contribute to Mercari from its inception. After Souzoh was established, he began to focus on technologies for new services in addition to design, development and operations. Currently, he manages the development group of Souzoh.
Suguru Namura
After gaining development experience as a freelancer, Suguru joined CyberAgent, Inc. in 2004. There, he was in charge of the development of new projects, such as those for media and social games etc. He joined Mercari in 2016. Focused on the US, he oversees the development of Mercari’s US service. In April 2017 he became the CTO.
Kenichi Sasaki
Software Engineer (SRE)
Kenichi joined Mercari in July of 2014, bringing with him his past experience as a system integrator and social game developer. He now works with the SRE team to construct a wide variety of new subsystems here at Mercari, including a deployment automation system.
Osamu Tonomori
Software Engineer
Osamu joined CyberAgent, Inc. fresh out of university in April 2011 where he worked to develop new services for their media-related projects. In July of 2015 he moved to AbemaTV, Inc. and helped with the development of their AbemaTV platform. He made a mid-career job change and joined Mercari in August of 2016, where he is now a part of Souzoh handling development of the “Mercari Kauru” app. Originally from Kanagawa Prefecture. Also a Gopher. ʕ◔ϖ◔ʔ
Yoichi Tagaya
Software Engineer (iOS)
Yoichi has been developing and releasing apps on the Apple Platform ever since Mac OS X first came out. He has a PhD in engineering and previously worked at a foreign firm located in Japan helping to develop software to be used for chemical analysis. Yoichi joined Mercari in January of 2017, bringing with him a wealth of freelance/startup experience, and now works primarily on the development of iOS applications aimed at the US market. He is also the author of Swinject, the de facto standard for the Swift Dependency Injection framework.
Tsuyoshi Yoshioka
Software Engineer (Android)
Tsuyoshi joined Sony Ericsson Mobile Communications Inc. (currently called Sony Mobile Communications) as a new university graduate back in 2007. Since then, he has worked to develop software for use on mobile phones in the global marketplace. Tsuyoshi has experience developing across multiple platforms, including FOMA, Symbian S60, and Android. He made a mid-career change and joined Mercari in March of 2016, where he primarily works to develop Android applications aimed at the US market. Oh, and he has a beautiful voice.
Takuma Yamaguchi
Machine Learning Engineer
Takuma has worked on pattern recognition and machine learning research since he was a student. Takuma is a Doctor of Engineering and has done research on image recognition, computer vision and voice recognition, and also train fare calculation algorithms based on operations research methods. After working in data analysis at a large social gaming company, he joined Mercari in 2016. He currently works on the server side, in addition to machine learning focused on photo recognition.
Shinji Tanaka
VP of Engineering,
Mercari Europe
Shinji holds a Doctorate of Information Technology. After spending time as a researcher at NTT, he joined Hatena, Inc. in 2006 and from 2010 worked to integrate their technological divisions, while also acting as a business officer. From September 2016, he joined Mercari as an executive officer, and is currently in charge of UK engineering. He has written many server-side engineering books in Japanese and regularly gives presentations.


Photo booth
Mercari KAURU
Ask the Speaker
UI / Technical Differece in JP&US
AI / Machine Learning
Test Automation Demo
Cafe space
If you are using a terminal that does not support 5 GHz,
please ask Mercari staff at reception.


Bellesalle Roppongi Sumitomo Realty & Development Roppongi-Dori Building 1st Floor/B1,

7-18-18 Roppongi,
Tokyo 106-0032

2-min walk from Exit 2 of Roppongi Station, Tokyo Metro Hibiya Line
4-min walk from Exit 4b of Roppongi Station, Tokyo Metro Oedo Line

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