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Senior AI Agent Engineer - AI Agent Development Section, Business Support Development Department (BSD)

Rakuten

Tokyo, Tokyo, JapanJobNo compensation foundPosted 5 days agoVerified open 4 days ago

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At a glance

Compensation
No compensation found
Location
Tokyo, Tokyo, Japan
Work Authorization
Not specified

Job overview

Rakuten, a leading global e‑commerce company, seeks an AI Agent Engineer in its Business Support Development Division. The role focuses on building next‑generation AI‑native solutions to unify merchant communication services, improve operational efficiency, and drive new revenue growth across the organization.

Skills & qualifications

RequiredNice to have

Skills

Web Application DevelopmentCode ReviewPerformance TuningDatabase SchemaSpring BootSoftware Project ManagementAutomated Testing FrameworkJavaLangChainLlamaIndexCrewAIMicrosoft AutoGenPrompt EngineeringChain‑of‑Thought ReasoningWeb Application DesignArchitectural ImprovementsDatabase Schema DesignIntegration With External SystemsWeb APIsJapaneseEnglishManagement of Large Scale Projects

Qualifications

7+ Years Web Application Design Experience7+ Years Code Review Experience7+ Years Performance Tuning Experience7+ Years Architectural Improvements Experience7+ Years Database Schema Design Experience7+ Years Integration With External Systems Experience7+ Years Web APIs Development Experience7+ Years Java (Spring Boot) Development Experience7+ Years Large‑Scale Systems Development ExperienceProfessional Working Proficiency in JapaneseTOEIC Score 800+ or Equivalent Business‑Level English ProficiencyManagement Experience for Large Scale Projects

Full job description

Job Description: Business Overview Rakuten is one of the leading E-commerce companies in the world. Our mission is to empower people and society through the internet while aiming at becoming the "Global Innovation Company."

Department Overview The Business Support Development Division (BSD) plays a crucial role in supporting various business operations that occur between users, clients, and Rakuten businesses from a systems perspective. Our division provides diverse services across four key domains: DATA, Business Support/Accounting, CRM, and AI Agent, which builds the foundation for leveraging AI across the entire Rakuten organization. We are committed to pursuing business process optimization and efficiency while delivering high value through our system offerings. AI Agent Development Section, established under BSD in January 2026, is dedicated to building next-generation AI agent frameworks that empower Rakuten’s diverse business units through AI technology. Our mission is to reshape the digital future of e-commerce by building AI-native solutions that empower Rakuten merchants, catalyze new revenue growth, and radically reduce operational costs. Our main goal is to unify Merchant Communication Services Consolidating fragmented communication services into a single, cohesive merchant interface to streamline communication and user experience.

Position: Why We Hire We are looking for an AI Agent Engineer to design and build autonomous AI systems that can perform complex tasks by interacting with tools, APIs, and environments. You will be at the forefront of AI development, moving beyond simple chatbots to create intelligent agents that drive business value.

Position Details Design and develop autonomous AI agents using LLMs and agentic frameworks. Build tool-use capabilities (Function Calling) for agents to interact with external systems and databases. Optimize agent workflows for reasoning, planning, and task execution accuracy. Evaluate and refine agent performance through rigorous testing and prompt engineering.

Work Environment

Mandatory Qualifications: ・ 7+ years of hands-on experience in web application design, code reviews, performance tuning, and architectural improvements. ・ 7+ years of experience in application development with a focus on database schema design and integration with external systems. ・ Extensive hands-on experience (7+ years) in the design and development of Web APIs. ・ 7+ years of experience in the development and operation of large-scale systems using Java (Spring Boot) ・ Experience with LLM orchestration frameworks such as LangChain, LlamaIndex, CrewAI, or Microsoft AutoGen. ・ Understanding of Prompt Engineering and Chain-of-Thought (CoT) reasoning techniques. ・Professional working proficiency in Japanese or higher.

Desired Qualifications: ・ Experience of management for large scale projects ・ Experience in evaluating agent performance using automated testing frameworks. ・ Knowledge of LLM performance optimization (latency reduction, cost management).

Other Information: Additional information on Location Tokyo

Additional information on English Qualification ・ TOEIC score of 800+ or equivalent business-level English proficiency.

#engineer #commerce #RakutenIchiba

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