Climbing the Tower that Even the Regressor Couldn’t

Story:

A friend who passed out while drinking suddenly said something strange. “Suhyuk, I’ve regressed.” “Regressed?” “Yeah, I’ve returned to the past.” “Are you crazy?” “You’re the only hope left for mankind.” And so, he was dragged into the Tower, but… it doesn’t matter! Regressor? Tower? Trials? Whatever they are, I’ll conquer this damn tower!