Ginco Inc. [ 2017/12 - Current ]

Ginco Inc.

• Platform Department (formerly SRE Department) Manager / Senior Engineer [-Current]

  • Main responsibilities

    • Formulating and executing annual roadmaps
    • Designing high-difficulty projects
    • Recruitment / Training
    • Globalization

  • Introduced bare metal for blockchain node infrastructure [2024]

    • Reduced infrastructure costs by 40%, saving 84 million yen annually
    • Reduced API cost per RPC by 1/2 to 1/4

  • Department globalization [2023-2024]

    • Hired 7 overseas engineers (India)

  • Revamped blockchain node infrastructure and migrated to Google Cloud [2022-2023]

    Google Cloud Day ’23 Tour

  • Established SRE Department [2021]

    • Formulated team mission and OKRs, built a self-directed team
    • Implemented SLOs and built SLO dashboards, achieving continuous improvement in collaboration with management

  • SLO improvement [2020]

    • Built monitoring infrastructure
    • Improved API response 90%tile latency by 5x

  • Cost reduction [2020]

    • Reduced infrastructure costs by 55% without performance degradation

• Tech Lead [-2019/12]

  • Enterprise cryptocurrency wallet system
    • Responsible for requirements definition, backend and infrastructure design and development
    • Newly adopted gRPC and microservices architecture
      • Balanced development scale and speed
      • Enabled non-backend engineers to develop through service division

• Backend Engineer [-2018/12]

  • Responsible for design and development of cryptocurrency wallet app

  Ginco - 安心・安全の仮想通貨ウォレット

MC DIGITAL Inc. [2021/03-2024/04] (Contract)

• Architect
  • Design and development of large-scale data infrastructure (data lake, ETL, data warehouse)
  • Design and development of ML systems (infrastructure)
• SRE
  • Incident response improvement
  • ML systems (AI Platform, Airflow, Dataflow)
    • Performance improvement
    • Test implementation
    • CI/CD
    • Reliability definition, monitoring
• Management support

Recruit Holdings Co., Ltd. [2017/04 - 2018/03]

株式会社リクルート

• Responsible for framework implementation, authentication development, and development guidelines for new Air series product
• Responsible for backend development of Air Wait

Presentations and Articles

• Improving Development Efficiency and Cost Reduction: Revamping Blockchain Node Infrastructure Using GKE

  Google Cloud Day ’23 Tour

• Speeding Up Cold Starts of Cloud Functions

  How we reduced cold start time of Cloud Functions at Ginco Inc.

  GincoにおけるCloud Functionsの利用とその高速化

• The Impact of Context Switching on Productivity and Its Countermeasures, Improvement Examples

  コンテキストスイッチの生産性への影響とその対策、改善例

• "A Study on the Number of Graftable Bugs in Automated Program Repair," Computer Software, volume 33, number 3, pages 81-87, August 2016. Soichi Sumi, Yoshiki Higo, Keisuke Hotta, Shinji Kusumoto,