In Japan, the term "Gyaru-Mind" is commonly used to describe an upbeat mindset associated with gyaru culture, often linked to proactive positivity and strong self-affirmation. While it is widely regarded as beneficial, "Gyaru-Mind" lacks an academic operationalization and practical method for internalization. In this work, we define a quantitative index, "GYARU-MIDX", built from eight text-based factors, and implement a dialogue agent named GYARU-AI that uses this index in real time. During conversation, the agent estimates a user’s score and produces brief, context-appropriate replies by choosing between advice and empathy, so responses are not just positive all the time. A live "GYARU-MIDX" view provides real-time feedback for reflection and practice. The current system is Japanese-only because it is trained on Japanese "gyaru" style. We describe initial design and modeling results and outline limitations and next steps.