Learn how Mercari implemented LLMOps practices to scale evaluation-driven development for their LLM applications serving over 23 million users on Japan's largest C2C e-commerce marketplace in this 20-minute conference talk. Discover how strategic investments in DevOps, MLOps, and LLMOps significantly improved developer speed and quality while enhancing both software quality and developer quality of life. Explore key LLMOps focus areas including prompt management, comprehensive evaluation frameworks, and LLM application observability that enabled successful deployment of ambitious AI projects. Gain insights into the open-source software tools and methodologies that were instrumental in delivering unparalleled customer value at scale, and understand how proper LLMOps implementation can transform the development lifecycle for large-scale AI applications in production environments.