I Became the Apocalypse's Physical(?) Therapist

Earth has been sold. [To whom?] To one of the rulers of the universe. [Who sold it?] Neo Mason, the faction that seized power after the apocalypse. Following the sudden apocalypse and the subsequent sale of Earth, Gong Won-gu worked as an engineer for the Resistance. “We have already traveled to the past several times. And we achieved results.” “That is….” “It is thanks to that that the Resistance exists today, though it will soon vanish.” “So, you need someone to go again?” “Yes. This is the last chance.” “The very last chance… and you chose me?” Just before the Resistance is annihilated. Though he didn't want it, he is given the chance to return to the past and set things righ...