Natsuki, Subaru

On the way home from the convenience store, he suddenly finds himself transported into another world. He has the ability that he calls "Return by Death" to go back in time when he dies, with only himself being aware of the reversal of time. Despite being a hikikomori and gamer in his real world, Subaru does a bit of workout and seems to know basic hand-to-hand combat, making him not completely weak.

While Subaru tends to not read the situation, he is loyal to those he holds dear, willing to help them, even if that means taking the thorny path. He has his resolve confirmed through the many situations and circumstances he faces in the fantasy world, originally having been one to always take the "easy" route. As a hikikomori, he is hopeful of the possibilities that being sucked into a new realm brings, but later realizes the realities of the predicament he is in. Ultimately, he resolves himself to be faithful and protective of the ones that he cares most about.

(Source: Re:Zero Wiki)