Re:Zero is an isekai where the protagonist's only ability is dying. Subaru returns to a checkpoint every time he's killed, keeping his memories while everybody else loses theirs, and the series treats that as the horror it obviously is.

The psychological toll is the actual subject. Subaru can't tell anyone about the loops, so he carries every death alone, and by the third arc he's visibly broken by it. Very few time-loop stories are willing to let the mechanic damage the character this much.

It's also structurally clever. Because the loops are the only way to gather information, Subaru's solutions come from accumulated knowledge rather than power, and the tension is whether he can survive long enough to learn what he needs.

Rem's arc across the second arc is the reason a very large portion of the fandom exists, and it's earned.

This collection covers Subaru, Emilia and Rem.