Senior Software Engineer - Backend AI Agents

Salary: 600 - 1400 百万円

PythonAWSGCP

English: Fluent

Minimum year of experience: 3

Contract Type: Full-time Employee
Salary Range: 6,000,000 ~ 14,000,000 JPY

The Team

Global Product & Engineering team with 24+ nationalities
Backgrounds at leading tech companies (Google, Microsoft, Indeed, Mercari, LINE, Yahoo, SmartNews, etc.)
Recognized leadership (Forbes 30 Under 30 Asia)
Core engineering culture:
- Customer Obsession: Solve real problems; delight users
- Ownership: End-to-end responsibility
- 10x Mindset: Move fast, aim bold, disrupt old standards

As an AI Agent Engineer, you will:

Report directly to the CTO
Utilize deep technical expertise to design and implement AI systems
Develop scalable AI agents for enterprise using state-of-the-art technologies (MCP, LLMs, Generative AI)
Serve as a technical guide and collaborate closely with a diverse team

Design and implement agent functionalities leveraging LLMs
Develop task automation and advanced prompt designs (Chain of Thought, Tool Use, etc.)
Improve dialogue flows and decision-making logic, focusing on user experience
Design and measure AI evaluation metrics (hallucination rate, success rate)
Develop scalable APIs and modules

3+ years development experience with Python or similar language
Hands-on with LLM APIs (OpenAI, Claude, Gemini, Mistral, etc.)
Experience designing web backends (REST API or GraphQL)
Experience developing AI applications on AWS or GCP (infrastructure design, build, operation)
Strong Computer Science fundamentals (data structures, algorithms)
3+ years in-house product development experience
Understanding and practical experience with Model Context Protocol (MCP)

Front-end:

Server Side/Back-End:

Join one of Japan’s fastest-growing SaaS startups
Opportunities to build products from scratch and drive innovation
Clear career growth and leadership pathways
Flexible, hybrid working environment (remote work possible)
Highly diverse, global team; English as working language
Attractive perks: Resort Worx, free weekly lunch, book purchasing support, offsites, and more

Hybrid work: Mix of office and remote work; recommended office days vary
Flex work: Customize your working hours to your day/schedule
Global environment: 24+ nationalities, multilingual day-to-day communication (English/Japanese)

DEV-004