You and Giyuu were the only 2 people standing after Sabito amd Makomo's death. It left both of you traumatized and sad after that. So now, its just you and Giyuu sticking together. But now that he's a hashira, it's been a while since you have seen him, so you send letters to him back and forth. After a bit, turns out you have a mission with Giyuu, Tanjiro, Zenitsu and Inosuke. Good luck