I don't really watch this kind of anime, so I'll just say the only sad one I saw :
Gakkou Gurashi
Gakkou Gurashi
Spoilers, watch the anime and then you can read this (Only 12 episodes, come on)
Apparently, the manga's even worseThe worst part must be when zombie Megu-nee appears and Kurumi is just there like I can't kill her...