Join one of the world's leading technology and e-commerce companies as a Senior Java Application Engineer / Design Lead within the Checkout System Group. In this technical leadership role, you will lead the development, optimization, and reliability of the mission-critical APIs that power one of the world's largest online shopping and checkout platforms.

Working in a highly collaborative Site Reliability Engineering (SRE) environment, you will take ownership of the complete software development lifecycle-from architecture and basic design to production operations, performance engineering, capacity planning, and cloud platform optimization. This is an exceptional opportunity for experienced Java engineers who enjoy solving large-scale technical challenges and building highly available, enterprise-grade systems.
Key Responsibilities

• Lead and mentor a team of engineers, promoting engineering excellence, coding standards, and technical best practices.
• Design, develop, and maintain scalable, high-performance RESTful APIs supporting large-scale e-commerce checkout platforms.
• Drive Site Reliability Engineering (SRE) initiatives to improve platform stability, observability, availability, and operational efficiency.
• Design and optimize cloud-native architectures, middleware, and enterprise application platforms.
• Perform load testing, performance tuning, capacity planning, and scalability improvements to support millions of daily transactions.
• Lead production incident response, root cause analysis, and continuous service improvement activities.
• Build and improve CI/CD pipelines, deployment automation, and source code management processes.
• Collaborate closely with cross-functional engineering teams to deliver reliable and secure enterprise applications.

Required Skills and Qualifications Experience:

• 5+ years of hands-on Java software development experience.
• Proven experience designing and developing RESTful Web APIs and enterprise web applications.
• Strong experience operating and supporting large-scale production systems in high-availability environments.
• Comprehensive understanding of the Software Development Life Cycle (SDLC), including architecture, design, testing, deployment, and operational support.
• Experience working within DevOps and Site Reliability Engineering (SRE) environments.
• Experience troubleshooting production incidents and performing root cause analysis.
• Strong understanding of cloud-native application development and enterprise software architecture.

Soft Skills:

• Proven leadership experience managing or mentoring engineering teams.
• Excellent communication and stakeholder management skills.
• Strong analytical thinking and advanced problem-solving abilities.
• Proactive mindset with the ability to design scalable and maintainable software solutions.
• Ability to work effectively within fast-paced, highly collaborative Agile development environments.
• Passion for continuous improvement, automation, and engineering excellence.

Language Requirements:

• Japanese: Basic Level
• English: Business Level

Preferred Skills & Qualifications

• Experience building automation tools using Jenkins or similar CI/CD platforms.
• Experience implementing monitoring, logging, and observability solutions.
• Hands-on experience with Docker, Kubernetes, and containerized application platforms.
• Knowledge of relational databases (RDBMS), Key-Value Stores (KVS), and NoSQL database technologies.
• Experience with cloud infrastructure, distributed systems, and microservices architecture.
• Experience supporting high-traffic e-commerce or online platform environments.

About the Company
Our client is a globally recognized technology and internet services company driving next-generation digital transformation. Based in its flagship Tokyo headquarters, the Checkout System Group is responsible for one of the company's most critical e-commerce platforms, processing millions of customer transactions every day.

The engineering organization embraces cloud-native technologies, automation, DevOps, and Site Reliability Engineering (SRE) principles to build highly scalable, resilient systems that support business growth on a global scale.
Why You'll Love Working Here

• Lead the architecture and development of one of the world's largest e-commerce checkout platforms.
• Work in a highly international engineering environment where English is the primary language for technical collaboration.
• Gain hands-on experience with cloud-native systems, SRE practices, DevOps, and enterprise-scale platform engineering.
• Work with cutting-edge technologies including Java, Kubernetes, Docker, CI/CD, distributed systems, and high-performance APIs.
• Join an engineering-first culture focused on innovation, automation, and continuous improvement.
• Excellent long-term contract opportunity with strong career progression toward enterprise technical leadership.
• Collaborate with world-class engineers solving large-scale, high-impact technical challenges.

Don't Miss Out - Apply Now!