as I pointed over Shrine Maiden, check Koishi's third eye.
Yep, that's right, Flandre managed to open Koishi's third eye with her wings. Just wait until the SDM actually prepares the mansion for christmas with all and the tree. Koishi will be head over heels for her then
I really can't blame Koishi since apparently, she needed ANOTHER eye just to take in the awesome. If I got to see those wings for myself, I would squee like as if I was in a candy shop.