Demon Slayer's Puppet Master

A person who shouldn't have appeared, a story that shouldn't have happened. What happens when a lonely soul feels warmth for the first time? What happens when a puppet has emotions and a heartbeat? What happens to the puppet when the warmth disappears? It's my first time writing a book. If there is any dissatisfaction, I hope everyone will take care of it. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.