Sr. Software Engineer

◆Role Overview This role is focused on building AI-powered tools that support sales enablement. As a Software Engineer, you will work on designing and developing product features that leverage AI technologies to improve how sales teams operate and create value for users. This is a high-impact position for engineers who are excited to work at the intersection of product development and applied AI. ◆Technologies Core Stack: • AI/LLM: OpenAI SDK, prompt engineering & optimization • Backend: Node.js, TypeScript, Effect (functional TypeScript) • Cloud: AWS (Lambda, DynamoDB, SQS, SNS, SES, CDK) • Integrations: Google APIs (Gmail, Calendar), Microsoft Graph API, Zoom API • Testing: Vitest • CI/CD: GitHub Actions, pnpm Note: The above technologies reflect our current stack. The team has the autonomy to make technology choices that best serve our AI-native product goals. You will be involved from the architecture and technology selection stage. ◆Key Responsibilities • Design, build, and operate AI-powered systems leveraging large language models (LLMs), including prompt engineering, output parsing, and evaluation pipelines • Architect event-driven workflows (Lambda, webhooks, queues) that enable AI-powered features to operate reliably at scale • Collaborate closely with product, sales, and CS teams to translate business needs into effective AI-driven product features • Own the full lifecycle of AI-powered products — from prototyping and prompt tuning to production deployment and monitoring • Evaluate and integrate emerging AI capabilities (models, APIs, tooling) to continuously improve product and model performance • Contribute to engineering best practices through code reviews, documentation, and knowledge sharing

• 4+ years of software engineering experience in product development • Hands-on experience building applications that integrate LLMs (e.g., Claude, GPT) — including prompt design, tuning, and output evaluation • End-to-end engineering experience from design and development through to production operation • Solid backend engineering skills (Node.js/TypeScript preferred) • Experience with event-driven or serverless architectures (Lambda, webhooks, message queues) • Strong communication skills and comfort working with cross-functional stakeholders ・Business-level proficiency in both Japanese and English (for Japanese, a JLPT N2 or higher certification is required). • Passion for continuous improvement and staying current with the rapidly evolving AI landscape

• Experience designing, building, and operating architectures on AWS • Familiarity with RAG (Retrieval-Augmented Generation) patterns, vector databases, or embedding-based search • Experience building multi-step AI workflows (e.g., tool use, chain-of-thought, planning) • Knowledge of SOLID principles, Clean Architecture, or Domain-Driven Design (DDD) • Test-Driven Development (TDD) experience