This position is closed and is no longer accepting applications.

Senior Software Engineer, AI Agent & Search - LegalOn

LegalOn Technologies Shibuya-ku, Tokyo July 6 2026
  • 💴 ¥10.3M ~ ¥25M annually
  • 🏡
    Partially remote
  • 🌏
    Apply from abroad
    Relocate to Japan
  • 💬
    Business Japanese
    Fluent English
  • 🧪
    Senior level
    5+ years experience required

About LegalOn Technologies

LegalOn Technologies Shibuya-ku, Tokyo

LegalOn Technologies is a global legal AI company that combines advanced expertise in artificial intelligence with deep knowledge of law and contracts. Since our founding in 2017, we’ve been focused on building AI-powered legal services that help legal and business teams work faster and more confidently.

Key benefits

  • Collaborative, Respect-Driven Culture
  • Comfortable and Supportive Work Environment
  • Cutting-Edge Technology and Expert Colleagues

About the position

LegalOn Technologies is a leading company in AI product development, and our search and recommendation platform is one of the most important, mission-critical systems behind the products we deliver. In particular, as search has become increasingly essential in recent years as a key enabling technology that expands the capabilities of LLM-powered applications, we are looking for a Senior Software Engineer who has a strong passion for technologies in this domain and is well-versed in software engineering.

In this role, as a Senior Software Engineer, you will take significant responsibility for designing, developing, and improving how search and recommendation features are integrated into our products. You will develop a deep understanding of how users leverage these capabilities within the product experience, and proactively take ownership not only of search and recommendation but also of broader product development. You will solve complex challenges to deliver the best possible experience for our users.

Responsibilities

Mission and Challenges

  • Leverage expertise in search, recommendation, and AI to maximize user value as part of a team responsible for improving specific areas of the user experience
  • Collaborate with product managers and related teams to explore various possibilities for what features to deliver to customers
  • Drive concrete and actionable development plans to ensure the successful delivery of product features
  • Contribute to broader product development beyond search and recommendation to enhance the overall user experience
  • Mentor team members in designing sustainable and highly maintainable software systems

What You’ll Do

  • Design, build, and deliver a wide range of search, recommendation, and Agent features/APIs
  • Integrate LLM-powered applications with search and recommendation features to expand product capabilities
  • Proactively maintain and operate search and recommendation systems to ensure high availability and performance
  • Collaborate cross-functionally to investigate production issues in search, recommendation, and Agent systems, establish quantitative evaluation metrics, and drive continuous improvements
  • Develop a deep understanding of user behavior regarding search and recommendation to contribute to broader product development and ensure a cohesive user experience

Requirements

  • 5+ years experience in software engineering
  • Experience in one or more of the following
    • Experience developing AI agent features leveraging LLMs
    • Experience developing large-scale search or recommendation systems
    • Experience developing or improving machine learning models
  • Experience designing and developing production-grade backend services using Python or Go
  • Experience improving development processes by leveraging AI tools
  • Knowledge of data structures and algorithms
  • Hands-on expertise in building highly reliable and performant web backend systems
  • Hands-on experience with one of the Cloud Infrastructure Services: AWS, GCP, or Azure
  • Business-level communication skills in Japanese (JLPT N1 or equivalent)

Nice to haves

While not specifically required, tell us if you have any of the following.

  • 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 machine learning and natural language processing.
  • Experience mentoring/training junior engineers.
  • Leadership experience in large-scale projects or teams (10+ members) with a proven track record of delivering results
  • Strong communication skills, with the ability to work effectively across diverse cultures in both English and Japanese
  • Experience contributing to product features across multiple domains or technology areas, beyond a single specialization

Compensation

¥10,300,000 ~ ¥25,000,000 annually.

Hiring Process

  1. 1

    Resume Screening

  2. 2

    Casual Interview

    We offer the option to start with a casual interview, depending on your preference.

  3. 3

    Interviews/Aptitude Test

    We will conduct a technical interview, a behavioral interview, and an executive interview. The number of interviews may vary depending on the position and may change during the selection process. We use external aptitude tests, such as SPI and reference checks.

  4. 4

    Offer Meeting

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