Senior Backend & Platform Engineer (Quality, Security & Reliability) - Cloud Strategy Office, Cloud Management Department (CMD)

Job Description Business Overview The Technology Platforms Division (TPD) drives the growth of Rakuten's ecosystem by delivering innovative, high-quality technology platforms characterized by integrated control and strategic partnerships. Within TPD, the Cloud Platform Supervisory Department (CPSD) develops and manages Rakuten's state-of-the-art cloud platform, empowering global scalability and accelerating innovation across its diverse business units. Department Overview The Cloud Management Department (CMD) leads Rakuten’s unified cloud infrastructure strategy by providing governance and essential tools to ensure seamless operation and high satisfaction among service providers and users. As the central point for strategy, planning, and process governance, we manage the cloud product portfolio, budgeting, quality, and security. Furthermore, we empower cross-departmental success through robust cloud foundation and management solutions. The Cloud Strategy Office develops financial intelligence, governance, and decision-support products for internal-cloud service providers and private- and public-cloud buyers. We help stakeholders improve cost, pricing, investment, quality, and multi-cloud strategy through reliable data products and strong financial partnership. Position Why We Hire The Cloud Strategy Office is expanding into a production financial platform that supports internal-cloud service providers and cloud buyers. The roadmap includes budget and forecasts simulation, internal unit-price analysis, automated reports, depreciation and asset detail, vendor-cost detail, anomaly tracking, and multi-cloud usage and cost data. We need a hands-on senior engineer who can build the backend, make integrations reliable, and own engineering quality as AI-assisted delivery increases. This person will ensure that plausible but incorrect changes are detected and corrected before they create financial, security, or reliability risk. Position Details ・ Build, modify, test, and operate production backend services and APIs in Python ・ Own integrations with source systems, including interface contracts, authentication, reliable ingestion, validation, and failure handling ・ Act as the technical lead and quality authority for the engineering work while remaining an individual contributor with no people-management responsibility ・ Review human-written and AI-generated changes, identify plausible but incorrect behavior, and make or guide the necessary corrections ・ Keep technical debt low through simple architecture, clear boundaries, automated tests, refactoring, documentation, and removal of obsolete paths ・ Own CI/CD and automated quality controls, including code review automation, testing, dependency and container controls, and secure delivery practices ・ Improve reliability, performance, observability, incident response, and recovery as the platform and user base scale ・ Work closely with the Financial Data & Analytics Engineer to provide trustworthy source data and stable product boundaries for business data modelling ・ Deliver roadmap capabilities with finance specialists, internal-cloud service providers, the Cloud Center of Excellence, data specialists, and internal-cloud buyers ・ Use English for cross-functional communication, documentation, technical review, and decision records Work Environment You will join a newly formed, small cross-functional team in the Cloud Strategy Office. The team combines engineering and finance expertise and works directly with the people who provide and buy Rakuten’s internal and public-cloud services. This role reports to the hiring manager and leads technical standards without line-management authority. The current environment includes Python, SQL, Flask, BigQuery, Google Cloud Storage, Parquet, DuckDB, HTML, CSS, JavaScript, Cloud Run, Cloud Run Jobs, Docker, Terraform, Jenkins, pytest, Ruff, mypy, and AI-assisted development tools. Candidates do not need prior experience with every named tool, but they