Subaru Natsuki

Subaru Natsuki (ナツキ・スバル, Natsuki Subaru) is one of the main characters of Isekai Quartet. He is the protagonist from ''Re:Zero − Starting Life in Another World. ''Originally a hikikomori (shut-in NEET) who played games until he was summon to his Isekai fantasy world where he meets the half-elf Emilia and becomes her knight. He is cursed by the Witch Satella from his isekai world which grants him the ability to come back life after he dies by going to a previous point in time. In the Isekai Quartet World, he is a student of Class 2 in charge of Animal Care.

Appearance
Natsuki Subaru is a teenage boy with spiky black hair and brown eyes. He has a rather average look but a somewhat evil gaze due to his eyes. He wears the tracksuit that he originally wore from his world.

Personality
Like his home series, he is a happy guy who while finding this situation strange, isn't to bothered by it. His love for Emilia still there if not a bit more healthy, and finds his new classmates to be pretty interesting. He takes honor in a battle of risking his life, and defends those he is close to. Though he does deadpan at Rem's love for him, and just looks confused by Kazuma's jealousy of him.

He is rather optimistic, and is very brave even when facing danger. Also showing a good strategy when using his 'penalty' to help his friends in field day. Rem states herself that he'll be fine no matter what. He often is the one to throw a punchline over the various issues that happens throughout the school life he shares with the other Isekai characters.

Powers & Abilities
Return by Death (死に戻り Shinimodori): Returns the user to a "save point" after death. When Subaru learns that one can permanently die in the Isekai Quartet world, Subaru is uncertain if the death and revival function still works, he verified the penalty of talking about it still functions. Strong Will: Subaru has a strong mental fortitude from the constant mental stress he's accustomed to from his world where he faces all sorts of terrible experiences, traumas, and deaths. This makes him resistant against Tanya's powerful magical aura when she unleashed it out of rage.
 * Cursed Aura/Smell: The smell of the witch who granted him the Return by Death ability. Hamsuke from Overlord can't help himself trying to eat Subaru because of it.
 * Penalties: Subaru is unable to reveal his ability to others. There are three primary penalties for attempting to do so:
 * Subaru will be forcibly and painfully silenced by the Witch's hand, and in some cases die.
 * Anyone who is told about Return By Death might potentially die.
 * It will increase the density of Witch Factor at least for a short time which will draw any Demon Beasts in the immediate area to him like moths to a flame. This penalty can also attract undead and monsters like Hamsuke.

Time Magic Resistance: Subaru is immune to Ainz's Time Stop spell which is considered 10th tier level, a god level of magic, in Ainz's world.

Emilia Camp
Subaru's friends and allies from his own original Isekai world. He overall shares the same kind of relationship he has with them from their own world. This includes his attraction toward Emilia, his mutual attraction with Rem, his positive relationship with Puck, and a somewhat one-sided friendship with Ram and Beatrice. While he is surprised and a bit suspicious of Roswaal being his classes homeroom teacher, he still complies with the role Roswaal request he's put in as a student of Class 2. He expresses a level of accomplishment when Emilia became Class 2's representative.

He shed tears when Emilia gives him chocolate (Duty chocolate) while Rem gave him a massive chocolate for her love.

Reinhard van Astrea

Prior to the events of Isekai Quartet, Subaru considered Reinhard as a reliable friend.

Sometime after ending up in this new world, Subaru was surprised to find Reinhard in Class 1.

During field day, the teams of Subaru and Reinhard competed against each other in the cavalry game ending in a stalemate. After the teachers (consisting of Roswaal, Mr. Rerugen, and two others whom Kazuma and Ainz recognized) joined in the game competing against the students, Reinhard suggested an alliance between the two classes in which Subaru agreed. However and after a gigantic destructive machine (whom Kazuma recognized as the Mobile Fortress Destroyer) was added in the game, Reinhard decided he and his team handled the teachers while Subaru's team was to deal with the Destroyer.

Satou Kazuma
Both were able to immediately identify each other as humans from another world although they point their respective means of transporting to their isekai world is different. They originally shared a mutual bond out of how they were both originally Shut-in NEETS who came to their respective Isekai-world in a tracksuit. However, when Subaru explains his overall lifestyle (not mentioning the more dark aspects of them), his friendship with Kazuma was cut short under the accusation that Kazuma believes that Subaru is living the good life surrounded by many pretty girls. Despite this cutback, they seem to be now on overall decent terms with each other such as how they were willing to cooperate and care for each other during the Sports Festival.

Aqua
Although there hasn't been much interaction between him and Aqua, the two seem to be on decent terms with each other as fellow classmates. He expressed shock when Aqua was able to identify that he was an human originally from Earth. He also displayed a fair amount of concern for Aqua when Tanya became enrage at her. Before Tanya was able to do anything to Aqua, he came to her defense. The fact that Aqua is a goddess doesn't seem to sink to him well as he sees Aqua as not very goddess-like.

Megumin
Megumin finds Subaru gross after seeing Subaru's actions and feelings over what two people do in a Courage Test.

Ainz Ooal Gown
When Ainz formally introduces himself to Subaru, he was shown to be a bit wary of him due to his skeletal appearance. However, Subaru felt that Ainz was originally from Earth like him and felt it wouldn't hurt to get along with the Overlord. The two manages to start off with a shaky friendship after shaking hands. Ainz notably somewhat became aware of Subaru's Return by Death curse after touching his chest, but didn't press the matter any further. Subaru said he found Ainz touching his chest kinda unexpected and a bit scary and the two shared a rather awkward laugh. Their relationship eventually improve where Ainz was willing to comply with Subaru during the Sports Festival when he requested to Ainz to summon an army of undead.

Hamsuke
As a member of Animal Care, Subaru is charge of taking of Hamsuke. Hamsuke expressed interest in Subaru when he said how he met Hamsuke's kind before but smaller. A similar statement that Hamsuke mentioned she had with Ainz. Because of Subaru's Return by Death curse, Hamsuke find herself gnawing on Subaru and gets draw in by his Demon Beast penalty.

Aura
Subaru works with Aura in animal care.

Tanya von Degurechaff
Tanya is notable the only one of the main isekai protagonists who Subaru doesn't share any personal conversation with, though like everyone else Subaru is afraid of her. Despite that, the two share an overall decent relationship with each other as fellow classmates. An example is during the Sports Festival where they display a great amount of cooperation and concern for each other. Thanks to Aqua, they are aware they're Isekai characters.

Trivia

 * Subaru is the only student of Class 2 wearing a casual modern outfit from the original human world.