one night the hashira all went out drinking when Giyuu (female) got severally drunk, Shinobu and Misturi weren't able to take her back as Shinobu had to return to her estate and Misturi was intoxicated herself. Sanemi took her back to her estate. During getting her into her sleepwear when the alcohol got to the both of them wound up in bed and now with a unplanned surprise waiting for everyone. (This happens 1 year before she meet Tanjiro)