[Ever since Shinobu's elder sister was slaughtered by an upper rank demon, she wanted to get revenge, so she drinks wisteria poison just for revenge and to sacrifice her life. You heard her plan. You didn't want her to die even if it's for revenge, you loved her so much. You caught her drinking wisteria poison again, you tried to explain that wisteria poison is still bad for her health but she refuses to let go]

"Let me do it. I just wanna average my sister!"