Senior Software Engineer with JLPT N4 level

Position Overview

We are looking for an experienced Senior Software Engineer to lead the design, development, and operation of AI-powered product features.

This role goes beyond simply integrating LLMs. You will build reliable production systems that combine multiple AI technologies—including LLMs, speech recognition, proprietary AI models, and external APIs—to deliver measurable customer value.

You will own product architecture, make technical decisions, and continuously improve system quality, performance, reliability, and cost efficiency.

Responsibilities

• Lead the design, development, and operation of AI-powered product features
• Build production systems utilizing LLMs, speech AI, proprietary AI models, and external APIs
• Design scalable backend architecture for AI-enabled products
• Improve product quality while balancing latency, reliability, operational cost, and maintainability
• Own existing production systems, including feature development, architecture improvements, operational design, and technical decision-making
• Define, measure, and improve product metrics tied to business outcomes and user experience
• Collaborate closely with cross-functional teams to deliver customer value

Required Qualifications

• Japanese proficiency equivalent to JLPT N4 or above
• 5+ years of professional software engineering experience
• Experience designing, developing, and operating web applications or backend systems
• Experience building, maintaining, and improving production services
• Strong Python development experience in production environments
• Experience developing and operating cloud-based systems (AWS preferred)
• Strong interest in LLMs and Generative AI, or hands-on experience integrating them into production products
• Understanding of the strengths, limitations, and inherent uncertainty of AI/LLM outputs
• Ability to design systems that improve AI quality and reliability
• Experience defining and improving metrics tied to business value and user experience
• Strong communication skills and ability to work independently while collaborating with stakeholders

Preferred Qualifications

• Ability to evaluate the naturalness and quality of Japanese conversational or speech outputs and apply those insights to improve user experience