Original name: Otome Gēmu no Hametsu Furagu Shika Nai Akuyaku Reijō ni Tensei Shiteshimatta
This is a manga adaptation from light novel series. In this chapter, the main female (Katarina Claes) is chloroformed by some mysterious guys. All she could say in the last scene was "what is this sweet smell?" and "why do i feel so sleepy suddenly?".
There is also an anime adaption which is currently airing every Saturday and I am pretty sure this scene will happen within next few episodes (will update later).
The wake up scene happens in the next chapter, however, is a bit disappointing as she wakes up as if nothing happened yesterday!
I found this on raw manga website.