AI Engineer - No Japanese needed - UP to 11M

Software Engineer — AI Agent Platform

Tokyo (Hybrid, 2–3 days/week in office) · Full-time

A note on fit: This is a platform engineering role — not a Data Scientist or ML Engineer position. We're looking for someone with a strong backend/infrastructure background who has experience building the tooling and systems that let other engineers ship AI features, not someone focused on model training, experimentation, or research.

Location: Candidates must already be based in Japan. This is a hybrid role requiring in-office presence, and relocation from outside Japan is not supported for this position.

About the Company

I'm recruiting on behalf of my client, one of Japan's leading fintech companies. They operate a cloud-based business platform helping companies solve financial and operational challenges through integrated cloud and AI-powered solutions, including a scalable ERP offering built for mid-sized and large enterprises.

A key initiative underway is building a state-of-the-art AI Agent Platform that lets product teams quickly experiment, prototype, and deploy AI-powered agents — giving teams shared infrastructure and best practices to build AI-driven features faster across the org.

About the Role

This role sits on the team building that AI Agent platform: the frameworks, SDKs, runtime systems, and tooling that let multiple product teams safely develop and deploy AI agents in production. It's a platform engineering role spanning both frontend and backend — ideal for someone who enjoys building platforms used by other engineers, solving distributed systems challenges, and shaping how AI capabilities scale across a large SaaS ecosystem.

Required Skills & Experience

• Must be based in Japan (hybrid, in-office role — no relocation support)
• 7+ years of software engineering experience building and operating web applications
• Strong backend and platform engineering experience (APIs, microservices, distributed systems)
• Experience building platforms, internal tools, SDKs, or infrastructure used by other teams
• Backend language: Go is a strong plus, but any modern backend language is welcome — legacy-only stacks are not a fit
• Experience with cloud infrastructure (AWS preferred), Docker, Kubernetes, and Infrastructure as Code (Terraform, Kubernetes manifests)
• Strong API design skills (REST/streaming), with a focus on developer experience and reliability
• Experience integrating LLM APIs (OpenAI, Gemini, Anthropic, etc.) into production systems
• Ability to own problems end-to-end, from design through production rollout
• Product mindset — proven ability to translate high-level requirements into clear technical solutions in close collaboration with Product Managers
• Experience mentoring engineers and contributing to technical design discussions
• Comfortable using AI-assisted development tools to improve engineering productivity

Nice-to-Have

• Understanding of AI agent patterns (tool use, function calling, memory, multi-turn conversations, guardrails)
• Experience building multi-tenant SaaS or developer platforms
• Familiarity with observability tools (Datadog, logging, tracing)
• Experience designing CI/CD pipelines and automated infrastructure workflows
• Comfortable working cross-functionally with product, security, and other engineering teams

Language Requirements

• Japanese: Not required, but a plus
• English: Business

Work Style

• Hybrid — minimum 2 days/week in office (3+ encouraged)
• Discretionary Labor System for Professional Work (subject to change to Flextime)

Benefits

• Full social insurance, neighborhood housing & moving allowance, salary-based rent deduction
• Health checks, flu vaccine
• Book purchase support, defined-contribution corporate pension, employee stock ownership plan
• Preferential rates on rental agency, housekeeping, babysitting, and online English lessons