仕事内容
LegalOn Technologies is a global leader in legal AI solutions, trusted by more than 8,000 companies and law firms worldwide. The company empowers legal teams to review and negotiate contracts faster, with greater accuracy and confidence. Operating across Japan, the United States, and Europe, LegalOn is the first AI company from Japan to surpass ¥10 billion in annual recurring revenue (ARR) and has raised over $200M from leading investors including SoftBank and Goldman Sachs. It also has one of the largest and most global AI teams of any startups in Japan. In 2025, LegalOn achieved its first M&A by welcoming Germany's Fides Technology into the group, further accelerating global expansion. LegalOn combines LLMs, intelligent Agents and intelligent AI-driven workflows. Beyond legal, the company now offers specialized AI solutions including "CorporateOn," "CXOn," and "DealOn" to support diverse business domains requiring high expertise. In partnership with OpenAI, the company is redefining the legal AI landscape and developing innovative solutions for the future of professional work. For more details about our company, products, and development organization: https://legalforce-recruit.notion.site/LegalOn-Technologies-Candidate-Handbook-17d82a58637480d2836ae138e5b5ee95 Mission and Challenges
Own the design, development, and operation of AI-native features centered on RAG, LLMs, and AI agents, going beyond model implementation to deeply integrate with UI/UX and business workflows to deliver truly usable AI experiences Lead end-to-end decision-making across model selection, inference architecture, RAG design, and agent design based on specific use cases, balancing both quality and speed Design and implement robust operational frameworks—including evaluation, monitoring, logging, and cost optimization—to continuously improve and maintain a reliable and trustworthy AI experience
What You’ll Do
Design and implement highly reliable agent-based LLM workflows for production environments Build execution infrastructure for AI agents by integrating with external services and internal APIs Evaluate and select appropriate external models, frameworks, and services based on use case fit Translate user needs into concrete requirements through stakeholder discussions, and collaborate cross-functionally to design optimal agent-based solutions Establish testing frameworks and monitoring systems to evaluate agent performance, and visualize key metrics Define development processes and quality standards through code reviews and comprehensive documentation Identify and address technical challenges to ensure the accuracy, reliability, performance, and scalability of AI systems, driving continuous improvement
Required Skills / Qualifications
5+ years of development experience in at least one of the following: Python, TypeScript, or Go Hands-on experience building applications using LLM APIs (e.g., OpenAI, Anthropic, Google Gemini, Mistral) Practical experience developing AI agents (e.g., LangChain, CrewAI, OpenAI Agents SDK, Google ADK, MCP) and working with context engineering Experience designing and implementing RAG systems, including embeddings, vector databases, and retrieval algorithms Experience improving generation quality through prompt optimization and the design of evaluation metrics Solid foundation in natural language processing (NLP) and experience building data pipelines Japanese proficiency equivalent to JLPT N1
Preferred Skills / Qualifications
Experience building and operating search infrastructure using Elasticsearch, OpenSearch, Vespa, or similar technologies Experience designing systems that integrate knowledge graphs or structured data with RAG Experience designing and operating systems in cloud environments such as AWS, Google Cloud, or Azure Experience preprocessing and normalizing unstructured text data, such as customer emails, FAQs, and product documentation
7.7million to 15million yen per year
19F, Shibuya Sakura Stage SHIBUYA TOWER, 1-1 Sakuragaoka-cho, Shibuya-ku, Tokyo 150-6219, Japan This is not a fully remote position. Hybrid work is required, and visa support is available.
Full-time
Working hours: Full flex system without core hours Overtime work beyond designated working hours: Yes Break time: 1 hour
3 months
Work Environment & Tools
Choice of laptop: Mac or Windows (Mac with US keyboard available) Access to generative AI tools: ChatGPT Enterprise, Notion AI, Gemini for Google Workspace, Slack AI Access to developer tools: Claude Code, Cursor, GitHub Copilot, Devin, Codex, Figma AI, and more Side jobs permitted with prior approval
Professional Development
Self-development support available for books, online courses, certifications, and more Language learning support
Time Off
Weekends and national holidays off Paid leave and year-end/New Year holidays Special leave: sick leave, work-life balance leave, birthday leave Maternity leave, childcare leave, and nursing care leave
Health & Welfare
Social insurance coverage: Health insurance, employee pension insurance, unemployment insurance, and worker’s compensation insurance Influenza vaccination support No indoor smoking (a designated smoking room is available in the building) Employee stock ownership program Certified as an “Eruboshi” company (recognized for promoting women’s participation and advancement in the workplace)
会社名: 株式会社LegalOn Technologies
設立: 2017年4月
所在地: 東京都渋谷区桜丘町1-1 渋谷サクラステージSHIBUYAタワー19階
201.5億円（資本準備金等含）
約632名（役員含む／2026年4月時点）