SRE Engineer for Payment and Card Issuance Platform Reliability at a Mizuho FG Group Financial Platform

Company Overview

UPSIDER is a fintech startup founded in 2018, committed to creating a global financial platform that supports challengers. Their innovative financial services for corporations include an AI-powered credit evaluation technology that shortens traditional credit decisions from a month to as few as 2-3 business days. Their ecosystem includes next-generation business cards, invoice payment services, growth funds, accounting automation, and a business leaders community. UPSIDER recently joined the Mizuho Financial Group, combining startup agility with mega-bank reliability and scale.

Role Summary

This role focuses on the Site Reliability Engineering (SRE) team newly established for the Processor Team that supports core payment and card issuing processing infrastructure. The system handles an average of 70,000 daily transactions and has processed over one trillion yen cumulatively. The primary objective is to ensure 24/7 stable operation and to evolve the product into a reliable, secure, and scalable platform that meets rigorous financial institution requirements.

Key Responsibilities

• Design and implement infrastructure to enhance the availability and resilience of the payment system.
• Scale the infrastructure to accommodate increasing transaction volumes.
• Strengthen observability through distributed tracing, structured logging, alerting, and develop mechanisms for detecting outages and anomalies.
• Lead incident response, troubleshooting, and drive permanent solutions to prevent recurrence.
• Improve security and compliance of the payment platform.
• Renew messaging infrastructure and batch processing to enhance scalability and maintainability.
• Enhance developer experience and optimize infrastructure costs by improving CI/CD pipelines and code management.
• Continuously address technical debt from an operational perspective.

Technical Environment

Primary programming languages include Go (main), Java, and TypeScript. APIs use gRPC and REST. Data stores include Google Cloud Spanner and MySQL. Messaging layers utilize NATS JetStream and Google Cloud Pub/Sub. Infrastructure is built on Google Cloud, Kubernetes, Istio, Helm, Kustomize, and Terraform. Observability tools include Grafana, Loki, Prometheus, OpenTelemetry, and Cloud Trace. CI/CD is managed with GitHub Actions and Argo CD. AI-assisted development tools such as Claude Code, Codex, and Cursor are regularly used.

Team and Culture

The position is part of the newly formed Processor Team exclusively focusing on SRE. The company fosters a tech-first culture embracing rapid, high-quality development cycles, agile methodologies including mob programming and thorough code reviews. Decision making is bottom-up, encouraging experimentation and collaboration across teams to achieve business success. UPSIDER values respectful communication and user-first thinking.

Qualifications

• Experience in designing and operating cloud platforms such as AWS, Google Cloud, or Azure.
• Proficiency in establishing monitoring and alerting systems using tools like Datadog, Prometheus, or CloudWatch.
• Expertise in designing and improving CI/CD pipelines with GitHub Actions, ArgoCD, CircleCI, or similar.
• Practical skills in root cause analysis and resolution of system issues, including log analysis and load testing.
• Strong communication skills for collaborating with teammates and developers.

Preferred Experience

• Design and operation of SLI, SLO, and SLA reliability metrics.
• Infrastructure as Code management, particularly with Terraform.
• Deployment and maintenance of container orchestration platforms like Kubernetes.
• Backend product development experience.
• Experience launching or growing an SRE team.
• Promoting post-mortem culture and documentation best practices.

Desired Attributes

• Alignment with UPSIDER’s mission to empower challengers.
• Ability to thrive in uncertain environments while enjoying the work.
• User-focused mindset, proactively suggesting design and specification improvements.
• Respectful interaction with colleagues at all levels.
• Active collaboration across departments to drive business success.

Compensation and Benefits

• Annual salary range: 10,400,000 to 15,000,000 JPY (variable based on evaluation).
• Biannual bonuses dependent on grade and performance.
• On-call duty allowance for emergency responses on nights and holidays; approximately 3-4 times per month on rotation.
• Full flexibility in work hours and remote work available.
• Trial period of six months.
• Weekends, national holidays off; paid leave, year-end/new-year holidays, summer vacation, maternity and childcare leave available.
• Transportation allowance, company-issued PC, complete social insurance coverage.
• Startup leave of 3 days granted upon joining.

Location

Tokyo office located at 7-15-7 Roppongi, Minato-ku, Tokyo 106-0032, Japan.