Haken Senior Data Scientist - LLM, NLP & GCP | Tokyo

Join one of Japan's largest technology and digital commerce companies as a Senior Data Scientist specialising in Large Language Models (LLMs), Natural Language Processing (NLP) and Generative AI.

Based in Tokyo, this contract opportunity offers the chance to develop production-grade AI solutions that improve the quality, consistency and usability of massive Japanese-language product catalogues and master data.

You will work within a central data organisation responsible for supporting a large digital ecosystem spanning e-commerce, digital content and fintech services. Your work will help transform complex, unstructured Japanese product information into reliable, structured data that supports better digital experiences.

A key part of the role involves designing and deploying LLM-powered applications, Retrieval-Augmented Generation (RAG) pipelines and automated data normalisation solutions. You will combine advanced NLP techniques with practical machine learning engineering to address real business challenges.

You will also help modernise legacy manual processes by introducing AI agents and automated enrichment workflows, incorporating human-in-the-loop oversight where appropriate to maintain quality and reliability.

Beyond model development, you will establish statistical evaluation frameworks, benchmark datasets and systematic testing approaches to assess LLM outputs, monitor data quality and improve the reliability of AI-driven decisions.

Working with data scientists, machine learning engineers, business stakeholders and international technology teams, you will translate complex requirements into scalable solutions while balancing computational costs, execution speed and business value.

This position is particularly suitable for an experienced Senior Data Scientist, NLP Engineer, LLM Engineer, Generative AI Engineer or Applied Machine Learning Specialist seeking to apply advanced AI technologies to large-scale Japanese-language datasets.

Please note: This opportunity is open only to candidates currently residing in Japan.

Key Responsibilities

• Translate complex business challenges into practical, production-ready machine learning solutions and automated AI pipelines.
• Conduct exploratory data analysis (EDA) on large volumes of Japanese-language text, product catalogue information and master data to identify quality issues and improvement opportunities.
• Design, develop and deploy LLM-powered applications that support automated data enrichment, classification and normalisation.
• Build and optimise Retrieval-Augmented Generation (RAG) pipelines, using relevant information to improve the quality and usefulness of model outputs.
• Apply prompt engineering, structured outputs and advanced NLP techniques to improve the consistency and accuracy of AI-generated results.
• Transform legacy manual processes into AI-driven automated workflows and autonomous agents, incorporating human-in-the-loop review where needed.
• Establish statistical evaluation methods, benchmark datasets and quality metrics to assess LLM performance, data accuracy and model reliability.
• Use Python and SQL, including BigQuery, to extract, process, analyse and model complex datasets.
• Evaluate trade-offs between model performance, computational cost, processing speed and measurable business impact.
• Collaborate with cross-functional engineering, data and business teams to communicate findings, support deployment and continuously improve AI solutions.

Required Skills and Qualifications

Experience:

• 5+ years of hands-on professional experience in data science, machine learning and advanced natural language processing (NLP).
• Proven experience designing, developing and optimising Large Language Model (LLM) applications for practical business use cases.
• Strong understanding of Retrieval-Augmented Generation (RAG), prompt engineering and structured LLM outputs.
• Advanced Python programming skills for data modelling, machine learning development and analytical workflows.
• Strong SQL skills, including experience with analytical databases or data platforms such as Google BigQuery.
• Demonstrated ability to conduct complex data extraction, exploratory analysis and data quality investigations.
• Experience translating business requirements into deployable machine learning models, AI applications or automated data pipelines.
• Ability to develop systematic approaches to model evaluation, statistical analysis and data-driven decision-making.
• Current residence in Japan is required for this contract opportunity.

Soft Skills:

• Excellent logical reasoning, structured thinking and analytical problem-solving abilities.
• Ability to evaluate technical trade-offs involving computational cost, processing speed, model quality and business impact.
• Strong stakeholder communication and presentation skills, with the ability to explain statistical findings and model evaluations clearly.
• Collaborative approach to working with data scientists, engineers, product teams and business stakeholders.
• Proactive mindset towards improving AI workflows, strengthening data quality and adopting emerging technologies.
• High attention to detail and commitment to reliable, measurable and production-ready machine learning solutions.

Language Requirements:

• Japanese: Business-level proficiency is sought for analysing Japanese-language datasets and collaborating with local stakeholders. The position's initial language classification indicates conversational Japanese.
• English: Business-level proficiency is sought for cross-functional communication and technical collaboration. The position's initial language classification indicates basic English.

Preferred Skills & Qualifications

• Experience with LLMOps, including deployment, monitoring and ongoing evaluation of production LLM applications.
• Knowledge of prompt injection defences, personally identifiable information (PII) handling and responsible AI practices.
• Experience designing LLM-as-a-Judge evaluation workflows to assess output quality and model performance.
• Familiarity with knowledge graphs, ontology design and structured knowledge representation.
• Practical experience with attribute extraction, data enrichment and normalisation of unstructured Japanese-language text.
• Hands-on experience with Google Cloud Platform (GCP) and cloud-based data or machine learning workflows.
• Regular use of modern AI coding assistants to support software development, experimentation and engineering productivity.

About the Company

Our client is a major Japanese technology company operating one of the country's largest interconnected digital ecosystems, spanning e-commerce, digital content and fintech services.

The organisation supports hundreds of millions of user touchpoints through a wide range of digital platforms and consumer-facing services.

Its central data organisation manages extensive volumes of product master data, providing a foundation for data-driven innovation, machine learning applications and the company's ongoing digital transformation.

As the business continues to invest in advanced technology, Generative AI, Large Language Models and intelligent data processing are becoming increasingly important in improving the accuracy and usefulness of information across its platforms.

The company's international engineering environment brings together data scientists, machine learning specialists, software engineers and business teams to develop practical solutions to complex data challenges.

Joining this team provides an opportunity to contribute to large-scale AI and NLP initiatives, improve Japanese-language product data and help deliver better digital experiences across a major consumer technology ecosystem.

Why You'll Love Working Here

• Join one of Japan's largest digital technology ecosystems, supporting major e-commerce, content and fintech services.
• Work on large-scale Generative AI, LLM and NLP applications with direct business relevance.
• Apply RAG, prompt engineering and AI agents to challenging Japanese-language data problems.
• Help modernise manual data enrichment and normalisation processes through intelligent automation.
• Gain experience building production-grade AI pipelines and robust LLM evaluation frameworks.
• Develop expertise in Python, SQL, BigQuery and Google Cloud Platform within a data-intensive engineering environment.
• Collaborate with international data scientists, machine learning engineers and technology specialists.
• See the impact of your work on product data quality and consumer experiences across widely used digital platforms.
• Enjoy complimentary daily meals at the company's employee food hall.
• Benefit from a hybrid working arrangement, supporting flexibility throughout the working week.
• Receive comprehensive health, labour and employment insurance coverage.

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