Senior Software Engineer – Backend AI Agents

Responsibilities

Leverage your expertise in AI agent technology to participate in cutting-edge development. Reporting directly to the CTO, you will utilize your deep technical knowledge to design and implement AI systems, while pursuing product quality and technical superiority. You will collaborate closely with team members and play an active role as a technical guide.

In this role, you are expected to develop scalable AI agents for enterprise use, utilizing the latest technologies such as MCP, LLMs, and Generative AI.

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

Requirements

• 3+ years of development experience in Python or a similar language.
• Experience utilizing LLM APIs (e.g., OpenAI, Claude, Gemini, Mistral).
• Experience designing web backends using REST API or GraphQL.
• Experience in developing AI applications using AWS or GCP, and in designing, building, and operating the infrastructure on AWS or GCP.
• Proficient in Computer Science fundamentals, including data structures and algorithms.
• 3+ years of development experience on an in-house product.
• Understanding and practical experience with Model Context Protocol (MCP).

Nice to Have

• Experience using agent-related libraries such as LangChain or Semantic Kernel.
• Experience developing prototypes with consideration for UI/UX integration.
• Experience building GPTs or custom chatbots.
• Business-level English proficiency.

Tech Stack

Front-end

• TypeScript, React
• Libraries: Storybook, Jest
• Hosting: Amplify

Server Side/Back-End

• Infrastructure: AWS, Elastic Beanstalk
• DB: Aurora, ElasticSearch
• Languages: Go, TypeScript
• Analysis Environment: Athena
• Framework: Express
• Monitoring: DataDog
• Others: AWS Lambda, AWS Batch, AWS API Gateway, AWS Glue

Why Join?

• Work at one of the fastest growing SaaS startups in Japan with strong financial growth.
• Engage in innovative new product development and build things from scratch.
• Enjoy abundant leadership and career development opportunities.
• Flexible and fully remote-friendly work arrangements.
• Be part of a global, English-speaking team.
• Receive great benefits and perks (e.g., resort work programs, book purchasing, weekly free lunch, offsites, etc).

Working Style

Remote Work

We offer a remote-friendly environment and utilize tools such as Zoom, Google Meet, and Gather to maintain high-quality communication and smooth operations.

Flexible Work

Customize your daily working hours according to your team's needs. Each employee meets a monthly requirement equating to 8 hours per working day.

Work-Life Balance

We value a healthy work-life balance and provide an environment where you can prioritize personal time or choose to focus on work as you prefer.

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Position Details

• Position: Senior Software Engineer – Backend AI Agents
• Employment Type: Full-time employee
• Annual Salary: ¥8,000,000 – ¥25,000,000
  Actual offer will be decided based on your experience and skills.
• Location: Tokyo, Japan (Remote friendly)
• Probation Period: 6 months (same conditions during probation)

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Learn More

• Culture Book
• YouTube Introduction