Sadaaki Hirai
Software Engineer, Engineering Manager, Hiring Manager
info [at] sadah.dev
Taking photograph, Reading books, Visiting Art museums

Now, I am interested in creating engineering organizations that can scale, and in product development.

The following is the main content of our work to date.

  • Building engineering organizations
  • Development and operation of an engineer evaluation system
  • Hiring engineers
  • Project Management
  • Introduction of a company-wide evaluation system
  • OKR / 1on1 operation
  • Direct management of a team of about 20 people
  • People management of engineers, designers, product managers, and foreign members.
  • Product Development (Ruby, Ruby on Rails, JavaScript, Java)


January 2022 -September 2023

Mercoin, Inc. (Mercari, Inc.) / Engineer Manager, Software Engineer

As an engineering manager, I oversaw people management (1-on-1, goal setting, evaluation, etc.) of software engineers and product development management. Until the product’s release, I worked with teams of up to 20 people as Manager of Managers. In developing the crypto asset sales office function, I was responsible for the overall Backend development. I managed the specification review, schedule management, and performance testing in cooperation with many stakeholders. As a result, the product was launched without any major incidents.

Jan 2022 -December 2021

Mercoin, Inc. (Mercari, Inc.) / Software Engineer, Backend

I transferred to Mercoin, a subsidiary of Mercari Group, as a Software Engineer. I went through the internal transfer selection process to work as a Software Engineer. After the transfer, I worked as a software engineer, designing and implementing microservices using Go and GCP. I also focused on recruiting to build up the development team.

July 2019 -June 2021

Mercari, Inc. / Mercari JP Engineer Hiring Manager

I was in charge of engineer recruitment for Mercari JP, developing strategies for new graduates and mid-career recruitment. I worked on improving the engineering selection process, new graduate engineering training, D&I, etc.

November 2018 - June 2019

Mercari, Inc. / Engineering Manager of Managers at Mobile Department

As the engineering manager for Mercari JP Mobile as a whole, I worked on people management and mobile development process improvement for about 40 people in total. The main initiatives are as follows.

  • Creating the team roadmaps and conducting the actions needed to make them a reality
  • Two-way sharing/reporting of information between my team and the company’s management
  • Setting goals, evaluating, and providing feedback to software engineers
  • Training and mentoring software engineers
  • Hiring software engineers
  • Assigning engineers to projects

January 2015 - October 2018

Goodpatch, Inc. Chief Technology Officer

Immediately after joining Goodpatch, I was an engineering leader for the prototyping tool Prott, where I worked on project management, team building, programming (Ruby/Rails/JavaScript), and performance tuning. After assuming the position of CTO, I created the engineering organization, formulated the engineering evaluation system, developed the environment, and hired engineers. In addition, as Vice President of Products, he was also responsible for managing a cross-functional team of about 15 people to drive product development and achieve business goals.

August 2012 - December 2014

Kakaku.com, Inc / Software Engineer at Tabelog

I worked as an engineer for a restaurant search service called Tabelog, where I developed an Internet reservation service. I coded programming with Ruby on Rails and JavaScript and developed Internet services.

2004/04 - 2012/07

NEC Nexsolutions / System Engineer

I worked as a system engineer. I coded programming with Java, Linux, and so on.

Other Information


Please feel free to send me your work request using our contact form or email.