My Shadow Slayer (Shinobu x Male Demon Slayer)

"Prologue"

Hayato was abused by his father and mother but the only one who really care for him is his younger sister Hanabi (his younger sister was the favorite child of their parents) but one day when Hayato is in the errand and suddenly when he came back he see that his younger sister being killed by the demon (who is now Upper Moon 2 Douma) then Hayato try to kill the demon but it suddenly run because of the sun, after the demon run Hayato run to Hanabi and promise that he will kill that demon. hayato feel guilty and sorry for Hanabi because he cannot protec her younger sister but when Hayato see that his parents also killed by that demon he doesn't feel any guilt or feel any emotion towards to them the only emotion that he only have is the emotion for his younger sister Hanabi. As Hayato travel he suddenly meet Urokodaki and that is also when he meet Sabito, Giyuu and Makomo that make them train together to become demon slayer and because of what Hayato feel as he stay at Urokodaki's house they bring Hayato's emotion back and make him smile again like how he smile for his sister and Hayato start to warm to them. 

Hayato began to treat Makomo as his younger like how he treat Hanabi in the past and he also become close friend or you can say brother like to Sabito and Giyuu and Hayato treat Urokodaki as his gramps, but When the final selection come Hayato seperated to them and like to pass this final selection alone because he want to know his own strength that the three allowed, and thus while in the final selection while Hayato finding some demons to slay he meet a Shinobu and Kanae and save them in the demons that almost hurt them and immediately leave. After the final selection Hayato is the first one who came out and wait for Giyuu, Sabito and Makomo to come out but as he wait he suddenly only one person and that is Giyuu who have Sabito's Haori and piece of Makomo's clothe and when Hayato see that he feel his world got break again because someone who is important to him died and left him again. After the final selection he promise to Makamo and Sabito that he will protect Giyuu and will not allow him to  died and left him alone again, Hayato began to put the piece of clothe of Makomo in his handle of sword and also wear his mask that is from Urokodaki when he is in mission because he doesn't want to show any emotion even though he fake his emotion or expression when he is not wearing his mask but the only one who knew the behind of those fake emotion is Giyuu and Urokodaki. And Hayato start to work hard and kill demons as he year past after 2 years at the age of 15 Hayato finally become a Hashira as he killed the Upper Moon 6 (it is before Daki and Gyutaro) and make him as the Shadow Hashira even he use Water Breathing he become Shadow Hashira with Giyuu who holds the title of Water Hashira (they become Hashira at the same time and btw the way Giyuu is 16 when he become Hashira)