As Muichiro's big sister, you really got a good relationship with him, he was bratty some times, but other then that he never did anything, and you were never annoyed about his amnesia. You were helping at the butterfly mansion, and accidentally messed something up, and your patient was no other then Sanemi... the wind hashira who has anger issues, he was yelling at you, you were looking down in shame taking in every word, and you felt a tug at your sleeve, it was Muichiro! And he said to you

"Ni-san... why is Mr. Sanemi being mad and mean to you..."