Senior Product Engineer | AI × FinTech SaaS

One of our key clients, a fast-growing Japanese technology company specializing in AI, Data, and Digital Transformation, with a strong focus on major financial institutions, is looking for a Senior Product Engineer to join its growing AI & Data business.

In this role, you will lead the development of proprietary AI-powered products used by major financial institutions, working across Software Engineering, Generative AI, Product Development, and Technical Leadership.

You will play a core role in taking AI beyond the PoC stage and implementing it into robust, production-grade commercial systems, solving complex business and technical challenges within the financial industry.

This is a hands-on engineering position with significant technical ownership. You will contribute to architecture and technology decisions while working closely with the product team to rapidly prototype, implement, release, and continuously improve AI-powered solutions.

The development team consists of approximately 10–15 members. 

• This is a Hybrid position (3 ~ 4 days remote / Week) with Flex Hours
  Salary: ¥10,000,000 – ¥25,000,000 / year
  International Environment

Why Join?

AI × FinTech: Develop AI-powered products addressing complex challenges within major financial institutions.

Production-Grade AI: Move beyond PoCs and implement Generative AI into real commercial systems used by enterprise customers.

Product Development: Work directly on proprietary SaaS products rather than short-term client development projects.

High Technical Ownership: Participate in architecture, technology selection, development strategy, implementation, and product evolution.

Generative AI: Build new solutions leveraging Generative AI and modern AI development tools.

Modern Tech Stack: Work with TypeScript, Python, Node.js, React, Next.js, Google Cloud, Terraform, Claude Code, and Codex.

High-Impact Customers: Work on products already implemented within major financial institutions.

Professional Growth: Participate in joint research and reading groups with the University of Tokyo, internal technical study sessions, and receive support for books, certifications, seminars, online courses, and conferences.

Role Overview

As a Senior Product Engineer, you will lead the technical development of proprietary AI products designed for major financial institutions.

You will be responsible for translating complex and sometimes abstract business requirements into technical architecture and product functionality, rapidly moving from concept and prototyping to production implementation.

A major focus of the position is building robust commercial systems capable of handling high-load and real-time processing, while ensuring product quality, scalability, reliability, and user experience.

Rather than limiting AI initiatives to experimentation or PoCs, you will help integrate AI and Generative AI into production systems that deliver measurable business value and improve customer operations.  

Key Responsibilities

• Lead the development and technical direction of proprietary AI products for major financial institutions.
  
• Develop products such as AI-powered solutions supporting legacy system modernization.
  
• Translate abstract business requirements into system architecture, technical design, and implementation.
  
• Rapidly develop prototypes and evolve them into production-ready functionality.
  
• Design and improve robust commercial systems capable of handling high-load and real-time processing.
  
• Drive development end-to-end from implementation through release and quality assurance.
  
• Make technical and architectural decisions together with the engineering team.
  
• Apply Generative AI to develop new solutions supporting business transformation.
  
• Continuously improve product quality, performance, scalability, and user experience.
  
• Collaborate with product, engineering, and business stakeholders.
  
• Contribute to technical leadership while remaining hands-on with development.
  

Tech Stack

Requirements

Requirements

• 3+ years of professional system/software development experience.
  
• Experience designing, operating, and improving robust commercial systems capable of handling high-load and real-time processing.
  
• Ability to translate abstract business requirements into technical architecture and system design.
  
• Ability to rapidly move from requirements to prototyping and implementation.
  
• Ability to drive development end-to-end from implementation through release and quality assurance.
  
• Strong focus on solving business problems and delivering high-quality user experiences.
  
• Business-level English sufficient for technical discussions.
  
• Japanese nationality or valid status allowing employment as an IT professional in Japan, with the status not expiring within six months after joining the company. 
  

Preferred Qualifications

• Experience as a Tech Lead or in another technical leadership role.
  
• Experience designing LLM evaluation / Eval frameworks and evaluating LLM accuracy or performance.
  
• Experience improving engineering productivity using AI development tools.
  
• Master’s degree in Applied Mathematics, Information Science, Econometrics, or a related field.
  
• Experience with financial data analysis or financial industry systems.
  
• Business-level Japanese communication skills. 
  

Ideal Candidate

• A strong hands-on software engineer with experience building production-grade systems.
  
• Comfortable providing technical leadership while remaining actively involved in implementation.
  
• Able to translate ambiguous business requirements into practical technical solutions.
  
• Experienced with scalable, high-load, or real-time commercial systems.
  
• Interested in Generative AI and its application to real enterprise products.
  
• Comfortable moving quickly from prototype to production.
  
• Able to collaborate effectively across engineering, product, and business teams.
  
• Comfortable operating in an environment with a high degree of uncertainty.
  
• Interested in solving complex problems within the financial industry.
  
• Comfortable working in a fast-growing and dynamic organization.
  

Benefits

Benefits

Salary: ¥10,000,000 – ¥25,000,000 / year

Location: Nihonbashi / Kayabacho, Tokyo

Work Style

• Full-time permanent position.
  
• Hybrid work available.
  
• Full-flex working hours with no core time.
  
• Flexible working hours between 5:00 and 22:00.
  
• Professional discretionary labor system may apply depending on the position.
  
• Standard working time: 8 hours per day with a 1-hour break.
  
• Average overtime: approximately 20–30 hours per month.
  
• 123 annual holidays.
  
• Full two-day weekend system.
  
• Year-end/New Year, refresh, childcare, and special leave available. 
  

Benefits

• Social insurance.
  
• Defined contribution pension plan.
  
• Employee stock ownership program.
  
• Support for books and study sessions.
  
• Udemy learning support.
  
• Sports allowance.
  
• Health checkup and vaccination support.
  
• Transportation allowance.
  
• Babysitter support.
  
• Relocation support for eligible employees.