Blade of the sky

Okimoto comes from a poor family, so they don't have much money for Okimoto to spend anything on. So they sell haoris for a living. But one time when Okimoto left her home to work and get more money for her family, she came back late at night and saw that her family has been slaughtered by a demon. She doesn't want the demon to find her but she also seeks revenge, so she trains herself to go through intense training, making her muscles physically stronger. She went to final selection as the same time Tanjiro did, at that time she and Tanjiro were already friends. After training for so many years, she passed final selection at last and succeeds to become a demon slayer. She finds her way to the Ubuyashiki mansion, and was accepted by the master. She then had explained how she was intensely training herself for a few years, how her ancestors had passed down a breathing style down to her, Sky breathing. After 6 months , she was strong enough to become a hashira, shocking Tanjiro. Now she searches for the demon who had slaughtered her family 2 years ago.