
what i got from the spoilers, is that before she went back in time she carried a sword (mls sword) that she couldnt use but needed to turn back time, and he was in this word the whole time (idk like his soul thing), and because he is a sword master he remembers everything what the fl did, so this is why he has a big chrush on her

I’m a novel reader, you pretty much got it but to reiterate (obviously novel spoilers)
Echi specifically always kept the holy sword on her physical person because it was Yurien’s sword. The holy sword always has a conscious so when time was turned back Yurien was able to keep his memories. Iirc it was only after Yurien saw Echi during cadet applications that the holy sword shared all of the memories of the past with Yurien.
Anyway Yurien witnessed the 11(?) years of Echi searching for giosa and fighting for her life which is why he’s so observant / quick to notice when Echi’s unwell. It also made him wants to stay by her side which made his crush evolve into being madly in love (He’s a big simp) ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄
I still don't understand on WHY he likes her??? Like from what I've seen from the flashbacks they barely even talked to each other or even hanged out together??? All she feels for him is guilt for ending his life and yet he is over here feeling obsessed with him??!!