Yuri is the visual novel player that have found all the bad ends and the good end but is trying to play once again because they believe they can reach the True End.

Something bugs me: previously each loop were different timelines, so when last episode Setsu went through the portal, I thought they were just going to a different loop / timeline.

Timelines (loops) themselves are separate enough that real-Yuri gotten erased by gnosia in one loop is enough to have bug-Yuri exist in it stably, without real-Yuri existing in other loops affecting the current loop.

But they seemed to make a distinction here that Setsu went to a different universe which supposedly is totally disconnected to the one we are currently in, and impossible for Setsu to return to and pass on the silver key to past-Yuri.

Or am I reading this totally wrong?