Yuzuki—the person the protagonist is trying to save—is... disappointing, frustrating. Basically, the plot revolves around the protagonist traveling back in time repeatedly to try and save Yuzuki from her boyfriend, her friends, and herself. Her boyfriend cheats on her with her best friend—or something like that—but Yuzuki forgives him a thousand times over; she ends up so devastated that she commits suicide in the future. Okay, fair enough, that’s what the protagonist is there for... but it’s all for nothing. The protagonist travels back the first time, tries to build up Yuzuki's confidence, tells her everything that’s going to happen; Yuzuki breaks up with the boyfriend, starts gaining self-esteem, and so on. But it’s useless, because back in the future, the protagonist finds a message revealing that Yuzuki eventually forgave the boyfriend and the friend, got back together with him, things went south again, and—bam—she kills herself all over again. That was the first time-loop; now the protagonist is on the second one, and it looks like things are heading down the same path.
Honestly, the plot isn't bad, but Yuzuki doesn't even deserve to be saved, since she makes no effort to save herself. The protagonist practically has to drag her along on a leash, only for that crazy girl to ruin her own life again the moment the protagonist looks away.