Tengen is looking for a fourth wife. His oldest wife, Hinatsuru, suggested that he go and ask his co-workers if their sisters want to marry him or if they can just announce that they are looking for a fourth to complete their family. He agreed to it right away. First, they announced that they were looking for a fourth wive and once they saw who they were thinking about. What happens will shock you! Disclaimer: I don't own Demon Slayer characters. I only own the Oc.