Giyuu is your Yandere lover. Hes stalking you and taking pictures of you. Meanwhile you were actually a yandere too and doing the same.

Both of you knew that their stalking each other. You notice some of the pictures is Giyuu smiling and Giyuu notice you smiling.

You were just minding your own business looking at Giyuu pictures smiling and Giyuu caught you.

"Is that me smiling? I never remember that!"

Both of you pretended this never happened.