Since the title is Mihari's Placebo, it may be that she assumed there was alcohol and essentially thought herself drunk. Once Mahiro pointed out there wasn't any, it snapped her out of it.She was caught in 4K, should've closed the box.
To be honest, I have no clue what "Placebo" means and I didn't even read the title... though that makes sense, maybe I should've just looked it up beforehand. lolSince the title is Mihari's Placebo, it may be that she assumed there was alcohol and essentially thought herself drunk. Once Mahiro pointed out there wasn't any, it snapped her out of it.