Together forever [Muichiro x Y/N]

You and Muichiro, along with Yuichiro, were close friends pretty much since you were born. After one night in summer, when Muichiro and Yuichiro disappeared after a demon attack, even when everyone, including your sister, thinks they're dead, you're convinced that they're both still out there somewhere. Then one night, your older sister sacrifices herself to save you from a demon. Completely left alone, you set out on a journey to become a demon slayer at the age of 9. It didn't take you long to become a Hashira. Only around 2-3 months. And after so long, you get reunited with Muichiro Tokito, the Mist Hashira. But he's changed.