I also dont know what a dungeon is but from what i understand, it is essentially a created space and theres a clear condition requirement for people to get out of it. Some clear conditions involve killing the main monsters (like a rift) but if can be as easy as just fulfilling conditions, kinda like an escape room. In this world, dungeons are not as high risk as rifts. Also, this CEJ memorial dungeon was a space made by HYS of a previous timeline.
Ok so now. This LSY and CEJ in this dungeon are both from the current timeline. However, the HYS who made this, as well as the CEJ whose memories it was based on was from a different timeline. idk if first or second but all will be revealed in the next chapters.
Iirc, theres a theory where there are 3 lifetimes now.
One is where LSY died first (the one where he didnt awaken), another is where CEJ died first (the one where we see LSY crying and honeybee has her hair cut). Both dont have the rift scenario, and thats what makes this 3rd lifetime way different than the previous ones.

this chap was cute but can anyone explain this dungeon???? i kinda don't understand. is this lee sayoung from a diff timeline? and is this euijae from the timeline we've been following..?