TECH-S-101/EN- Software Engineer - Search, AI

LegalOn Technologies is a global leader in legal AI solutions, trusted by more than 7,500 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

【Key Responsibilities】
The Search and Recommendation group at LegalOn Technologies is responsible for a wide range of search, recommendation and agentic features in multiple rapid-growth services. LegalOn Technologies is a leading company of LegalTech in Japan, and Search and Recommendation is one of the most essential and mission-critical systems for our services. We are looking for a skilled Software Engineer passionate about technology to design and implement various search/recommendation features and solve complex challenges to provide the best search experience to our customers.

■ What Mission and Challenges You’ll Take On

• Collaborate with product managers to explore what exciting features we would deliver to our customers.
• Break down large tasks into smaller ones and deliver new functionalities or improvements, following the development plan/design the Tech Lead or Project Leader makes. You will also be a project leader for smaller or sub-projects, making a practical development plan and taking responsibility for the delivery.

■ What You’ll Do

• Design, build, and deliver a wide range of search, recommendation, and Agent features/APIs.
• Identify performance and accuracy bottlenecks in LLM-powered applications and improve them, as well as implement functional extensions such as integration with search/recommendation features.
• Proactively maintain and operate search and recommendation features/APIs.
• Collaborate with team members and other teams to investigate performance and accuracy issues in search, recommendation, and Agent systems in production environments, establish quantitative evaluation metrics, and drive improvements.

• 3+ years experience in search and software engineering.
• Basic knowledge of data structures and algorithms.
• Hands-on expertise in building web backend systems.
• Hands-on experience with one of the Cloud Infrastructure Services: AWS, GCP, or Azure
• Ability to communicate in Japanese on a daily basis (JLPT N2 or compatible experience)

• MS or Ph.D. degrees in Computer Science, Mathematics, or other technology-related majors.
• Hands-on experience in Apache Lucene, Elasticsearch, or Solr.
• Hands-on experience in developing Agent applications and related component technologies such as LangChain, Ragas, LlamaIndex, etc.
• Hands-on experience in Python.
• Hands-on experience in machine learning and natural language processing.
• Experience mentoring/training junior engineers.
• A proactive attitude towards learning and adopting new technologies, including AI-powered efficient development and task execution
• Strong communication skills, with the ability to work effectively across diverse cultures in both English and Japanese