Hello guys…
i can‘t remember the name of this one.
I can only remember that there was a guy and a girl having to do a trial where they have to walk a straight line for hundreds or thousands of miles. I know that the guy dies first and the girl finished. They they returned to the present.
I know its vague but maybe someone knows what i am talking about.
Thanks in advance.

What comes to mind is the webtoon called The Horizon by JH. The boy and girl walk quite a bit, and at the end it does go to the future. But the difference was that the girl dies and the boy lives.

Pretty sure this isn't it, but thought I'd throw it out here.

Uuhhh technically we learn this later in the story so.Take Me, I'm Yours?