Jikan Teishi Yuusha - Yomei 3-ka no Settei ja Sekai wo Sukuu ni wa Mijika Sugiru - Ch. 37 - Past and Stop

[Admmi]

I think this is going to have no consequences, he already comes back after dying, there is a chance all of this is an illusion and that saving her sister won't change much

 

[CinderSquall]

So we're getting some "fixing the future" time shenanigans. Does it only change the future if he succeeds in what it was he needed to do?

Considering Fury and Esther didn't remember what Sekai did when he initially "failed" I guess "success" is the only way to make an actual change happen.

 

[Victim_16]

I think if he succeed nothing will change in the main timeline. It's just an alternative route.