Subaru is the main protagonist of the series; he is a 17-year-old NEET who is suddenly 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”, which allows him to go back in time when he dies while retaining his memories of the previous timelines. He cannot tell anyone about this ability, because any attempt to do so causes him to black out momentarily as unseen 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.

After Subaru is injured in a public fight with Julius, he gets into a huge argument with Emilia, who decides to cut ties with Subaru and leaves him behind. Knowing that the mansion and village will be attacked, Subaru seeks help from the other royal candidates, but they all decline. While gathering an evacuation team, he encounters a legendary beast called the White Whale. After respawning, Subaru, having fallen into utter despair, has a serious conversation with Rem and asks her to run away with him. Rem, however, strongly encourages Subaru not to give up and confesses her love for him, already knowing that his heart is for Emilia. With newfound resolve, Subaru then decides that he will start again from zero. Subaru and Rem later battle against the White Whale after successfully striking an alliance with Crusch and Anastasia’s camps. Wilhelm kills the White Whale. After reconciling with Emilia, Subaru confesses his love for her, leading Emilia to tearfully thank Subaru for saving her. However, when Subaru questions his confession regarding Rem, Emilia gave no recollection of Rem for the second time, much to Subaru’s shock. Regardless of attempts to travel back in time through suicide, Subaru is unable to restore everybody’s memory of Rem whom he finds in a catatonic state.

In Arc 3, he officially receives a black ground dragon named Patrasche as his personal steed. In Arc 4 of the web novel, he enters into a contract with Beatrice and learns parkour and the use of whips as a weapon. As of the end of Arc 4, Subaru officially becomes Emilia’s knight.