Job Description: Department Overview The Marketplace Expansion Development Section develops and operates services such as the J.League Online Store, Furusato Nozei (Hometown Tax), Rakken, and Raxy. Additionally, the team is responsible for launching new EC-related services with the goal of expanding and growing Rakuten's marketplace. This is a highly challenging department where you can gain unique and valuable experiences that are distinct to Rakuten. Position: Why We Hire We are seeking an experienced Senior Backend Engineer who combines strong technical expertise with exceptional cross-functional communication skills and leadership experience. This role requires someone who can bridge the gap between engineering, product, and business stakeholders while contributing to backend development initiatives from early planning stages through implementation and deployment. Our development team is a global hybrid, with members based at HQ in Japan and in China. We are responsible for multiple systems, including the storefront, order management, and inventory management, with teams dedicated to each area. This position will be responsible for technical decision-making, coordinating with various stakeholders, and ensuring the delivery of high-quality backend solutions. This position requires strong business-level Japanese communication skills to effectively collaborate with internal stakeholders and partner departments. Prior experience managing a team or leading projects is highly valued. Position Details Primary Responsibilities - Participate in backend development projects from early planning and requirement definition through implementation and deployment - Coordinate with product managers, frontend engineers, and business stakeholders in Japanese to define requirements and project scope - Design and implement backend systems, such as Web API, batch with a focus on quality, performance, and maintainability - Write technical specifications and design documents following team guidelines - Designing and developing system components with clear responsibilities, considering overall system integrity. - Conduct code reviews and mentor team members when needed - Present technical proposals and progress reports to both technical and non-technical stakeholders - Take ownership of complex features and drive technical initiatives that improve team productivity What Makes This Role Unique - Leadership Opportunity: Opportunity to lead technical initiatives and mentor team members - Business Impact: Direct influence on product direction through stakeholder engagement - Tech Stack: Java21, Spring Boot 3, Spring Web MVC/Batch, Kubernetes, Google Cloud Spanner, Redis, Apache Kafka - Production Scale: High-traffic e-commerce platform serving millions of users - End-to-End Ownership: Involvement from early requirement gathering and technical planning to production deployment - Cross-Cultural Environment: Work with global teams across Japan and China - AI-Powered Development: Access to cutting-edge AI tools including Claude Code, GitHub Copilot, and other AI assistants to accelerate development Work Environment Backend Engineer Team Breakdown - 3-5 members Mandatory Qualifications: Experience & Leadership - 5+ years of professional backend development experience - 3+ years of team lead or people management experience in a team (approx. 3 members) - Experience in successfully delivering frontend projects from early-stage project processes (requirements gathering, technical planning, and system design) to deployment - Experience coordinating with cross-functional teams (product, frontend, QA) Language & Communication - Japanese & English: Business level or higher Core Technical Stack - Java & Spring Boot: Experience in designing and developing Java/Spring Boot in large-scale systems, with particular emphasis on architectural design capabilities considering performance, scalability, and maintainability. - RESTful API Design: Deep knowledge and mentoring ability regarding robust and extensible API design principles, as well as authentication and authorization mechanisms. - Relational Databases (MySQL/PostgreSQL): Expert knowledge and problem-solving skills in schema design, indexing strategies, query optimization, and transaction management for large-scale data. - Containerization (Docker) & CI/CD Pipelines: Experience in building and operating container technology and automated delivery pipelines, along with the ability to drive their adoption and improvement within the team. - Code Review & Best Practices: Fostering a code review culture and establishing/disseminating coding standards to maintain high-quality code. - Security Expertise & Audit: Deep knowledge of web security (including OWASP Top 10, vulnerability assessment, and secure coding practices), and the ability to lead the planning, execution, and proposal of improvements for security audits. Experience in evaluating overall system security risks and implementing appropriate countermeasures. Desired Qualifications: Leadership & Project Management - Experience with agile/scrum methodologies and sprint planning - Experience as a technical point of contact for stakeholder communication - Experience writing technical specifications, RFCs, or design documents - Familiarity with project management tools (Jira, Asana, Linear, Notion) - Experience working directly with product managers to define roadmaps - Understanding of e-commerce business models and metrics Technical Experience - Microservices Architecture: Deep understanding of inter-service communication, data consistency, API design, and problem-solving/design principles in distributed systems. - System Design: Experience and mentoring ability in designing large-scale systems considering scalability, reliability, maintainability, and extensibility. - Cloud Platforms (AWS/Azure/GCP): Deep experience in system design, deployment, and operation leveraging cloud-native services. - Performance Engineering: Ability to identify performance bottlenecks, formulate optimization strategies, and lead performance tuning efforts. - Testing Strategy: Ability to formulate and lead the implementation of comprehensive testing strategies, including unit, integration, and E2E tests. - Architecture Patterns (DDD, Clean Architecture, SOLID, etc.): Experience in building systems based on modern architectural patterns and design principles, and the ability to provide guidance on their application. Others Information: Additional information on Location Rakuten Crimson House, Tokyo, Japan #engineeringmanager #applicationsengineer #commerce #RakutenIchiba #EC #Backend #Spring #newservice #incubation Languages: English (Overall - 2 - Intermediate), Japanese (Overall - 3 - Advanced) In Japanese, Rakuten stands for ‘optimism.’ It means we believe in the future. It’s an understanding that, with the right mind-set, we can make the future better by what we do today. So we challenge ourselves to evolve, innovate and experiment, to create a better, brighter future for everyone. Today, our 70+ businesses span e-commerce, digital content, communications and fintech, bringing the joy of discovery to almost 1.3 billion members across the world. If you have any trouble logging in, please contact us here Rakuten Group, Inc.: rakuten-recruiting-info@mail.rakuten.com Please read the Application Requirements(EN) / 募集要項(JP) before applying. Our Diversity & Inclusion Policy and Application Documents Rakuten’s corporate mission is to “contribute to society by creating value through innovation and entrepreneurship.” We foster a culture that provides equal opportunities to those who share this founding philosophy and take on the challenge to transform society, regardless of age, gender, nationality, or any other status. Diversity is one of Rakuten's core strategies and a driving force for innovation. Because of this, you are not required to submit any of the following information in order to apply for our job positions. - Gender - Age - Photo - Nationality - Information not related to business, such as ideological beliefs, family structure, etc. * For legal compliance, we may ask you about your work eligibility. See the details