Because the symptoms of dementia arise from acquired brain dysfunction, they are highly individual and diverse. In this study, we constructed a patient experience (PX) space that enables users to experience dementia symptoms including hallucinations, and conducted co-creation with people with dementia. The conventional co-creation process had the challenge of long iterations until implementing the subjective experiences of people with dementia. Therefore, this study proposes an efficient hallucination modeling method through semi-automation of 3D model generation and behavior design using generative AI.