Job Description

Career Opportunity for a Java Software Engineer in Japan!

Company Overview

An e-commerce, fintech, digital content and communications company with more than 30,000 employees, and operations in 30 countries and regions.

Your Role and Responsibilities

This Department builds and operates the mission-critical systems that power these logistics services. Every package delivered to a customer depends on the reliability and performance of the platforms we develop. As a software engineer on our team, you’ll solve challenging distributed systems problems while building highly available backend services that support millions of customers and merchants across e-commerce platform.

• Build mission-critical systems that directly support one of Japan’s largest e-commerce platforms.
• Design and develop highly scalable backend services.
• Solve challenging distributed systems and performance problems.
• Work with modern cloud-native technologies.
• Influence technical design and architecture.
• Collaborate with experienced engineers across multiple platform teams.
• Take ownership of services from design through production operations.

Responsibilities

• Design, develop, and maintain scalable backend services using Java.
• Design reliable and highly available distributed systems.
• Improve system performance, scalability, and operational efficiency.
• Collaborate with platform and framework teams to improve developer productivity.
• Participate in architecture discussions and technical design reviews.
• Monitor production systems and contribute to incident response and continuous improvement.
• Write clean, maintainable, well-tested production code.
• Contribute to engineering best practices.

Experience and Qualifications

• More than 6 years of professional Java development experience.
• Deep expertise in Java, Micronaut, and modern backend development.
• Proven track record designing and delivering production-grade RESTful APIs and/or gRPC services.
• Proven experience designing, building, and operating microservice architectures at scale.
• Proven production experience designing event-driven systems with Kafka, including partitioning strategies, consumer group management, and failure handling.
• Deep experience building and operating scalable, highly available distributed systems.
• Hands-on production experience with reactive programming (Reactor, RxJava, etc.).
• Experience diagnosing and resolving distributed systems failures in production.
• Production experience deploying, scaling, and operating services on Kubernetes.
• Experience developing cloud-native applications on Kubernetes and private cloud platforms; AWS exposure is a plus.
• Experience with CI/CD pipelines and Git.
• Experience with capacity planning and performance tuning at scale.
• Strong understanding of software architecture principles and design patterns.
• Experience leading technical design reviews and making architectural decisions.
• Deep experience with relational and NoSQL databases (MySQL, Oracle, or Couchbase), including query optimization, schema design, and performance tuning.

Development Environment

• Java
• Kotlin (Gradle scripts and tooling)
• Micronaut
• Kubernetes
• Docker
• Kafka
• gRPC / Protocol Buffers
• REST APIs
• MySQL / Oracle / Couchbase
• Redis
• Gradle
• Git
• CI/CD (Jenkins)
• Elastic / Kibana

Additional Preferred Qualifications

• Experience working in Agile/Scrum teams.
• Experience with monitoring and observability tools such as Elastic/Kibana, Prometheus, or Grafana.
• Experience working on large-scale, high-traffic, mission-critical backend systems.
• Experience working in a globally distributed engineering team.
• Comfort working with AI-powered developer tools (coding assistants, internal chatbots, etc.).
• Excellent problem-solving and communication skills.

Good Reasons to Join

• Hybrid position in Japan
• Work with International team members

Work Location

Tokyo, Japan. Details will be provided during the meeting.