An epic. A long poem that chronicles the events and deeds of legendary heroes. There are few in anime and manga that truly meet this description. Survival is one of the few manga I have read that, I think, hits that bar. But why? And how? I don't think I can give an answer to either. It is simply a feeling, a raw emotion that cannot be put into mere words. To experience it, you just have to read it for yourself. I cannot promise that you will find Survival to be a good experience, or that the quality is of the highest tier, but
I can say that I think it is.