Slayer from the past (kny Oc x totcf crossover)

What if the TRASH OF THE COUNT FAMILY event and DEMON SLAYER event happen in the same world but the TOTCF event happen after 400 years and DEMON SLAYER event happen 400 years ago? Well this is a story of a slayer that have been alive for 400 years and now helping the mc of the story saving the world. How the slayer can be alive even after 400 years? Well turns into a half demon have it pro after all. Now let's see how the existence of this slayer can change the future

ps: previously I wrote this story in an acc called fiq_sy but the phone broken so I wrote it again here. Almost a year abandoning this story that I forgotten it exists also credit to whoever own the photo and video I'll be using and THIS IS MY AU SO DONT TELL ME THE DIALOGUE IS NOT THE SAME BECAUSE I'LL CHANGE IT TO FIT THE STORY

A/N: yes I can't draw for the love of my life so I use picrew and Pinterest to show the visual. Don't come to me for this. I'm an amateur writer but I accepted criticism about my writing skill. Feel free to voice your opinion but hate comment or toxic one will not be tolerated in here and I'm not gonna write 18+ scenes. There's children reading in this app