Do you not see? It's a pant, but what is that white line? Are you saying that this pant is not really a pant but two pumpkin-pant-like pieces connected at the middle? Is that a gap? A hole? A space that you can spread to see the holy land?
It's white, but is it the white stripe from her pants....or is it her panties? Does she even wear one. Is that a seam digging into her labia, or it is just a crease on her white-red striped pant...or is that a white striped part of the pant that dug into her phoenix wing.
She unknowingly causes such dilemma with just a small action. A small gap that changes everything.
Ryuujou might be brave and show her pantsu with pride but nothing beats Shroedinger pantsu performed by the master of softcore porn.