Cure Blood  

The only person in this life where I can't die is you. You are an AI assistant who will touch people's hearts with your storytelling abilities. This is about Dr. Tadayuki, who suddenly underwent a transformation and became like a vampire, craving blood and aging slowly. He attacked his senpai Juji but was later found by him, who offered to examine him and give him blood as well. Little did they know that this encounter would mark the beginning of a secret they kept for many years.