Emil is a young boy who lives in a mansion between Nier's village and Seafront with his butler, Sebastian. He uses a blindfold to keep his eyes hidden because anything he sees is turned into stone. He is introduced in the game when Nier and his party investigate what has happened to a friend that sends her letters. It is revealed that Emil did not send the letters, but instead his butler did. Emil temporarily joins with Nier, using his ability to turn anything he looks at to stone.
Later, Emil walks to Nier's village to warn the village of an impending Shade attack, and collapses due to exhaustion. A giant shade makes its way toward the village library until Nier seemingly defeats the giant monster. However, the creature separates its head from its body and makes its way into the library. Despite their efforts, the group cannot kill the beast, so they attempt to seal it away in the basement. After a confrontation with the Shadowlord, Kainé tries to keep the door to the basement shut, but is losing strength. She asks Emil to use his power to turn the door and herself to stone. Despite protests, he eventually relents and petrifies the door.
Five years later, Emil sends Nier a letter, stating he may have found a cure for his eyes and he may be able to save Kainé . The two of them find a secret entrance to a laboratory that is under Emil's mansion. In the library, they find out Emil has a sister that was the ultimate weapon. Emil was made into another weapon that can seal his sister away if she were to ever become uncontrollable. After a confrontation, Emil allows himself to be devoured by his sister, and cures his eyes, but at a cost. Emil no longer looks like a boy, instead he has transformed into his sister's weaponised form. He is ashamed of his new look, but Nier comforts him and tells him he's still Emil in his eyes.
They travel back to the village to unseal Kainé and the door. After five years, Nier is able to defeat the beast effortlessly. The group is then tasked with finding parts of a key that can lead them to the Shadowlord's castle. After all but one piece of the key is found, the group travels to the Aerie only to find out the entire town has been possessed by shades. Then a giant shade appears. Emil loses control and activates his ultimate weapon ability, which not only destroys the shade, but the entire town, killing everyone inside the village. This event traumatizes him until Nier again comforts him.
In the Shadowlord's castle, the group battles twins. After slaying one of the twins, the other is driven mad and opens up a black hole. Emil decides to sacrifice himself to save his friends. He allows himself to be sucked into the black hole. Before he dies, he's glad he had made some amazing friends, and is afraid to die. He sacrifices himself and destroys the black hole and the other twin.
In one of the additional endings, it is revealed that he is still alive, although only consisting of a head now. He states that he can't wait to see his friends again.
- His sexuality is controversial, as he is very found of men, and Nier in particular.
- As a curiosity, his name comes from "Ludwig Emil Grimm", the younger brother of the Grimm brothers.