 If you liked
I Am a Hero
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 ...then you might like
Mahou Shoujo of the End
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Mahou shoujo of the end and I am a Hero both involve Zombies Apocalypse as the main theme.
If you looking for more developed story, i recommend I am a Hero for you.
But if you looking for an unique Zombie apocalypse,and some fanservice, i think Mahou shoujo of the end fits you.