Yuuji Kaidou

He worked at a gas station in the near future until a life-threatening disease required him to be put into cryogenic stasis so that his state would not worsen. He awakens in the future to find that the Blue have destroyed everything he knew. He then begins his journey to Second Earth, learning to defend himself and others on the way. His mental state changes a lot during the series, as he sees more of the ruined earth and meets all the people left behind.