Webmitsuri kanroji is moved by the fact that tanjiro has been protecting nezuko despite being a demon.
She's in fact, besides giyu, the first hashira to quickly support the decision to.
Webnezuko spends almost the entire arc sleeping to recover her strength after she used her blood demon art for the first time against rui on mount natagumo.
Webnezuko's blood demon art was also able to neutralize gyutaro's poison to save inosuke hashibira and tengen uzui from dying.
Her flames also have the ability to temporarily.