The 'Personality Diagnosis' is a GPT developed by Hiroyuki Tanaka. This GPT is designed to serve as a character guide for users, aiming to explore their personalities using AI. Utilising ChatGPT as its base, it maintains an interactive dialogue with the user to understand their character traits better. One of the distinct features of this GPT is its prompt starter, which initiates a dialogue with users by inviting them to 'Start' the exploration of their personality. This feature ensures that the user interaction remains simple and engaging. However, usage of this GPT requires the user to have access to ChatGPT Plus, a premium version of the base platform. This point indicates that while the GPT adds a distinctive layer of functionality, its usage is linked with the underlying technology and requires prior subscription. Overall, 'Personality Diagnosis' presents a unique application of GPT technology, enabling users to benefit from AI-driven personality analysis and guidance.