【AI Engineer】~¥18M | Globally expanding AI SaaS

This record-breaking AI company with headquarters in the US and Japan ranks among the country's top profitable AI companies. With a continuous global expansion underway, they’re now looking for an AI Engineer to help advance their Search and Recommendations capabilities.The Search & Recommendation Group develops core features that power multiple fast-growing AI products, including search, recommendation, and agent capabilities. The Senior Software Engineer will design and improve critical systems that enhance retrieval and recommendation performance, directly influencing the quality of AI-assisted workflows.Key Responsibilities:Design, develop, and deliver large-scale search, recommendation, and agent-related APIs and featuresWork closely with product managers to define requirements and maximize customer valueDiagnose and resolve performance bottlenecks in LLM-based and search-driven applicationsMaintain and enhance production systems to ensure stability and scalabilityCollaborate across teams to identify and quantify issues, define evaluation metrics, and implement measurable improvementsSupport sustainable, maintainable system architecture and mentor team members in software design best practicesRequirements:Bachelor’s degree in Computer Science, Mathematics, or a related technical field5+ years of experience in software engineering or search system developmentStrong understanding of data structures and algorithmsPractical experience designing reliable, high-performance web backend systemsHands-on experience with at least one major cloud platform (AWS, GCP, or Azure)Business-level Japanese proficiency (JLPT N2 or equivalent)Nice-to-HavesMaster’s or Ph.D. in a related fieldPractical experience with Apache Lucene, Elasticsearch, or SolrHands-on experience with agent frameworks (LangGraph, Ragas, LlamaIndex, etc.)Proficiency in Python or JavaBackground in machine learning or natural language processingExperience mentoring junior engineers or leading large-scale projects (10+ members)Strong communication skills in multicultural teams (Japanese and English)Curiosity and passion for adopting new technologies such as AI-assisted development