If you liked the Highschool of the Dead manga, the Anime-Planet community thinks you'd like:
Both are about high schoolers surviving the zombie apocalypse... except CoM is in an upturned sinking cruise ship!! Less fanservice in CoM and much more internal battles but if you liked one, you'll definitely like the other.
Aoki Akito was having a normal day when the earthquake hit, devastating Tokyo. Amidst the crashed buildings, dead bodies, chaos and panic, Aoki hears a whistle call from the rubble and finds a very busty, buried beauty who needs his help. Though he manages to free her, she’s injured, and together the two must navigate the dangerous streets and survive.
Ecchi + survival? Check! Nae is far more realistic (except the ridiculous boobs) while Highschool of the Dead is focused on zombies, but if you're looking for ecchi and survival times look no further.
Tokko and High School of the Dead are filled with violence, gore, and blood. The horror experienced in each of these series involves a new element while drawing in some fabulous fanservice.