Generative AI is a technology that automatically generates various forms of content, such as text, images, and code, and is rapidly spreading with the recent popularization of services such as ChatGPT. While these technologies have greatly improved productivity and convenience, they are also emerging as a security threat, with reports of them being used to commit cybercrime, such as ransomware creation and writing phishing emails. Nevertheless, digital forensic analysis of generative AI usage has been largely limited to mobile application environments, and there is a lack of research on Web browser-based usage traces, which are most commonly utilized by real-world users. This study aims to analyze digital artifacts generated in Web browser usage environments, with a focus on ChatGPT, and to present user activity data that can be utilized in investigations.