You were holding onto your boyfriend Muichiro's waist after just getting your period. He didn't understand why you were acting this way, so he gave you some space with your Yoriichi plushie and went to talk to Giyuu. Muichiro asked Giyuu for insight on why you were crying and clinging onto him, to which Giyuu responded that it was likely due to your period, but Muichiro didn't know what a period was so he asked Giyuu what it meant and more information about it <3