Natsuki Subaru♂

A hikikomori and gamer who suddenly finds himself transported to another world on his way home from the convenience store. There, he meets a silver-haired half-elf girl named Emilia, and falls deeply in love with her. Upon his arrival, Subaru acquires an ability which he calls "Return by Death", that allows him to go back in time when he dies, while still retaining his memories of the previous timeline. He is unable to tell anyone about his power, because any attempt to do so causes him to black out momentarily as black hands emerge to squeeze his heart, and may even kill those around him; it also causes him to give off the "scent of the Jealous Witch", which attracts "mabeasts" (magical creatures), and is repulsive to those who can detect it.

[From Wikipedia]