2017–
Bringing development in-house
Starting with no engineers on staff, hired interns and full-time engineers and set up code review, CI/CD, and team rules to bring development in-house.
I build places where builders do their best work.
Nagaaki Hoshi
星 永亮 / ほし ながあき
I joined Rakuten in 2010, where I developed Rakuten e-NAVI, the member website for Rakuten Card, and went on to work as an Oracle DBA, a development team lead, and a technical director for new businesses.
In March 2017, I joined Yourmy Star Inc., then a six-month-old startup, as its first engineer. I brought development of the service, originally built by an outside contractor, in-house and set up the engineering team. I also head the product department, where I have managed a product organization that grew to about 25 people, built up engineering hiring and an evaluation system, led the move from AWS to Google Cloud, laid the groundwork for using data, and brought generative AI into daily operations and development.
What I care about most is building teams and systems that do not depend on a few exceptional people, where everyone can do their best work and keep creating value as things change.
Career
- Work
- Study
- Speaking
Brought generative AI into operations and development
Proposed Google Agentspace (now Gemini Enterprise) to make customer support replies more efficient, and the team put custom agents into daily use. Introduced AI tools such as Cursor and Cursor Bugbot for the engineering team.
Became a councilor of the Forest Foundation
Completed the move from AWS to Google Cloud
Finished moving the main products, a step-by-step effort that began in 2021. The new serverless setup handles peak demand in the busy season.
Completed the MOT program at Tokyo Institute of Technology
Master of Technology Management (Professional Degree). Presented research from the program at the 2nd Annual Conference of the Computational Social Science Society of Japan (CSSJ2023).
Entered the MOT program at Tokyo Institute of Technology
Scaled up engineering hiring and built an evaluation system
Set hiring KPIs and reviewed them regularly, growing the team to more than 10 full-time engineers. Defined expected roles for each grade and built an evaluation system around them.
Became head of the product department
Manages engineers, designers, and product managers.
Started the podcast Koiki.fm
A show where two engineering managers at startups talk about technology and organizations. I co-host it.
Spoke at PHP Conference Japan 2018
"How code review turned beginner interns into full-fledged engineers" (in Japanese)
Joined Yourmy Star Inc. as its first engineer
As head of engineering, started by bringing development in-house and setting up the basics: code review, CI/CD, and team rules.
Technical director for new businesses at Rakuten
Planned and managed the restaurant search app Rakoo, and launched services for brick-and-mortar stores.
Won Rakuten’s company-wide monthly MVP award
As lead of the Rakuten e-NAVI development team, shipped "Itsudemo Edy Charge" with the team.
Oracle DBA
Built databases, designed data migration, and tuned performance for a major system upgrade.
Joined Rakuten, Inc.
Developed Rakuten e-NAVI, the member website for Rakuten Card, as a web application engineer.
Graduated from the University of Tokyo
B.Eng., Department of Urban Engineering, Faculty of Engineering.
Work
Organization and hiring
2019–2022
Engineering hiring
Opened new hiring channels and designed technical interviews. In 2021–2022, ran casual meetings and interviews myself, set KPIs such as scout messages sent and casual meetings held, and reviewed them regularly, growing the team to more than 10 full-time engineers.
2021–
Engineering evaluation system
Defined expected roles for each grade across design, operations, review, project management, and technical decision-making. Used for goal setting and reviews every six months, with two career tracks: specialist and manager.
Infrastructure
2021–2024
Moving from AWS to Google Cloud
Made the call to migrate and set up a team dedicated to it. In 2023, adopted a new backend built on Cloud Run and AlloyDB through Google Cloud’s Tech Acceleration Program. Worked hands-on on Terraform and infrastructure, and completed the move of the main products in February 2024.
Data
2021
Introducing KARTE
Decided to adopt KARTE and set up an environment where non-engineers can run A/B tests easily. Marketing and product managers now run their own experiments.
2024
Unifying ad data
Decided to adopt trocco and automated ad data transfers. Daily ad reporting that used to take one to three hours each morning now takes less than ten minutes.
Generative AI
2025–
AI in operations and development
Proposed Google Agentspace (now Gemini Enterprise) and worked on its infrastructure and agent development. Decided to introduce AI tools for engineers and shared AI news regularly at company-wide meetings so that using AI became the norm.
Yourmy Open Radio #1: Behind our Google Agentspace rollout (Japanese)
Rakuten
2010–2014
Rakuten e-NAVI
On the Rakuten Card member website, used by millions of people, handled new features from requirements through development and testing. Became team lead after working as an Oracle DBA, and won the company-wide monthly MVP award for shipping "Itsudemo Edy Charge".
2014–2017
New businesses and product management
As technical director for new businesses, owned budgets, development plans, and priorities. Hold a patent as lead inventor for a geofenced coupon system for brick-and-mortar stores.
Talks & media
Talks
- 2023.02A bibliometric analysis of digital literacyAcademic talk｜CSSJ2023 (Japanese)
- 2019.02Automating release notices with the Backlog API, Zapier, and SlackLightning talk｜Shibuchakomatamagawa Engineer LT #2 (Japanese)
- 2019.02Psychological safety goes both waysTalk｜Web Engineer Study Group #11 (Japanese)
- 2018.12How code review turned beginner interns into full-fledged engineersTalk｜PHP Conference Japan 2018 (Japanese)
Interviews & articles
- 2025.07Yourmy Open Radio #1: Behind our Google Agentspace rolloutRadio｜note / Yourmy Star Inc. (Japanese)
- 2022.09Building a strong, flexible team for a fast-changing businessInterview｜Wantedly / Yourmy Star Inc. (Japanese)
- 2021.10How to build systems and teams that thrive on changeInterview｜Wantedly / Yourmy Star Inc. (Japanese)
- 2021.08With Mr. Akashi, former CTO of Yahoo! JAPANConversation｜Wantedly / Yourmy Star Inc. (Japanese)
- 2019.10How a startup turns interns into a real part of the engineering teamInterview｜OCTOPASS (Japanese)
- 2017.07The thrill of shipping fastInterview｜Wantedly / Yourmy Star Inc. (Japanese)
Podcast & more
- Co-hostKoiki.fmA podcast where two engineering managers at startups talk about technology and organizations (in Japanese).
- 2020Reviewed the Japanese translation of "Escaping the Build Trap"O’Reilly Japan, 2020. Volunteered as a reviewer and is named in the acknowledgments.