Because this is so what happened after chapter 159. I mean, come on.
White hands trace the black outlines of butterflies on brown skin. Where her pale fingers pass, Soi Fong removes the killing marks she left on Yoruichi's perfect skin.
Dark hands flow over white skin. Where her elegant fingers pass, Yoruichi removes Soi Fong's clothing.
Soi Fong withdraws the butterfly from Yoruichi's face last of all, and oddly reluctantly.
Yoruichi annihilates any regrets Soi Fong might have had with one kiss. She uses teeth.
When they finish, Soi Fong leaves a parting gift. She strikes one last indelible butterfly on her master, lovingly bound to the flesh of her inner thigh.