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Full-stack Engineer (JAPAN AI)
- Tokyo
- Partial Remote
- Full-time
- May 26, 2025
JAPAN AI, Inc. was established in April 2023 as a group company of Geniee, Inc., a publicly listed company, with the aim of dramatically enhancing the potential of working people through AI technology. We leverage cutting-edge AI technology to drive research and development both domestically and internationally.
We focus particularly on the development of AI agents, providing innovative products and solutions that utilize large language models (LLM). This enables us to improve productivity and operational efficiency across various industries.
JAPAN AI leverages the advantages of being a startup, allowing for flexible and rapid decision-making, and quickly adopting the latest technologies to provide optimal solutions for our clients. Additionally, our diverse team with an international perspective enhances our competitiveness in the global market.
We aim to create new value and contribute to the progress of society as a whole through the transformative power of AI. Let's lead innovation through AI and create a future where technology enables people to achieve more.
Why We’re Hiring
With the rapid expansion of our business, we are seeking a Full-Stack Engineer who can lead research, development, and product implementation in advanced technical domains.
In particular, we urgently need to strengthen our engineering team to develop core backend frameworks, which are critical for advancing research and large-scale development in the AI Agent domain.
Position
Full-stack Engineer
Role: Member
As a Full-Stack Engineer, you will join our development team to lead the evolution of our AI products. You will be responsible for solving complex technical challenges in core functionalities and driving the development of products that continue to be chosen by customers.
Job Description
You will be responsible for developing SaaS applications utilizing Generative AI. Your role will include designing and building highly efficient and reusable systems, as well as developing complex web applications.
- Product Development Using LLM:
- Design and develop products leveraging Large Language Models (LLM).
- API Integration Projects:
- Lead projects to integrate multiple APIs and create new APIs.
- Design and Implementation:
- Perform design and implementation with a focus on performance and maintainability.
- Web Application Development:
- Develop frontend applications using TypeScript and Next.js.
Team Structure
Approximately 65 members are part of the development organization. Development is divided into the following groups:
- Client Solution Development
- In-house AI SaaS Development
- Common Infrastructure Development (Infra / Data / AI R&D)
Required Qualifications
We are looking for candidates with:
- Bachelor's or Master's degree in Computer Science, Software Engineering, Artificial Intelligence, Machine Learning, Mathematics, Physics, or related fields
- 3+ years of experience in web application development using modern frameworks.
- 2+ years of experience in server-side implementation.
- Proficiency in at least one backend language (e.g., Python, Java).
- Experience with cloud services (AWS, GCP, Azure) and understanding of container technologies (Docker, Kubernetes).
- Fluency in English and/or Japanese (business level or higher in at least one language).
Preferred Qualifications
Candidates with the following experience or skills will be highly regarded:
- Experience in developing SaaS web applications.
- Experience in designing and building large-scale, complex architectures.
- Basic understanding and interest in Generative AI.
- Ability to stay updated on the latest technology trends and share knowledge within the organization.
Tech Stack
- Languages: Python (for framework development), TypeScript / React / Next.js (for frontend development)
- Infrastructure: GCP (containers / Kubernetes), Docker
- Tools: Slack, Confluence, Linear, Google Workspace, GitHub
- Work Environment: Mac (Apple Silicon), dual monitors available
Learning and Development Support
- AI Tool Usage Support:
- Company covers the cost of using AI tools such as JAPAN AI SaaS services, Curosor, CharGPT, Claude, etc.
- Development Tool Support:
- If a desired development tool is paid, the cost is covered (up to 30,000 yen per year)
- Book Purchase Assistance:
- Company covers the cost of purchasing books for learning, such as technical books (up to 30,000 yen per half-year)
- Language Learning / Qualification Support:
- Company covers the cost of Japanese or English learning programs and qualification acquisition
- Refresh Allowance:
- Company covers the cost of services used for personal refreshment (up to 5,000 yen per month)
- e.g., gym, yoga, chiropractic, aquarium, movies, theme park tickets, etc.
- Housing Allowance:
- Housing allowance provided for those living in designated areas (up to 30,000 yen per month)
Work Style
- Hybrid Work: 3 days in office, 2 days remote
- Flexible working hours: Core time is negotiable
- Flexibility: Future consideration for more flexible work styles is possible
Why You’ll Love This Role
- Exposure to Cutting-Edge Technology:
- Work with the latest technologies, such as Generative AI and LLM, to deepen your technical knowledge.
- Creative Environment:
- Design and develop products with creative freedom, delivering user-friendly solutions.
- Growth Opportunities:
- Gain abundant career advancement opportunities in a rapidly growing startup.
- Sense of Contribution:
- Work in a small, elite team where your ideas and opinions directly impact the product.
Selection Process
CV Screening → Coding test → Multiple Interviews → Final Interview
(Reference checks are required before the final interview.)
Additional Information
This position will initially be hired by Geniee, Inc. and then seconded to JAPAN AI, Inc. (both companies share the same location and workplace).
There is a possibility of transferring to JAPAN AI, Inc. in the future.
About Geniee
Geniee actively utilizes AI technology in product development and is an in-house product.
With “GENIEE SFA/CRM” and “GENIEE CHAT”, users can create automatic summarization of minutes using ChatGPT. Geniee provides AI-related functions, such as automatic email creation, that help customers improve their business efficiency and productivity. Under these circumstances, they provide implementation consulting, product provision, and services related to AI technology.
In order to further promote research and development, they’ve established a new subsidiary, “JAPAN AI Co., Ltd.” in April 2023. JAPAN AI Co., Ltd. has a purpose of “passing down Japan’s traditions and using AI to increase the potential of businesses.” They develop and provide various AI products to improve the productivity of Japanese companies and revitalize the industry. In order to develop advanced products, they also conducting research in areas such as various large-scale language models such as ChatGPT and Generative AI.
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