Time Travel: Starting from Attack on Titan

How could I travel through time accidentally? "Others have traveled through the Destruction of Heaven and Earth, why can't I move!" … "Why is this place so dark and wet? It's over, I might as well go to hell." … Finally one day, a girl broke in. "Haha, I can finally see something. Huh? This is, Ymir!" "Then I am...!!!" This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.