Giger

Giger is a World Devil that appeared in Japan on the fifth night. She did not lose control of her mind upon becoming a World Devil, and reasons her way through the night, as well as holding amiable conversations with Alices rather than killing them. Still, she holds no qualms about killing those she is ordered to as well as anyone who attacks her, despite not seeming to hold any ill will towards those who do. She understands that the inhabitants of both Zera and Maze are only humans at war, and mildly protests whenever anyone implies otherwise.

World Devil form
As a World Devil, Giger has a large, triangular head with several floating masks on it. She is otherwise humanoid. The triangular head is light colored, ending near her neck with a stepped section that has stripes on the last section and meets in a small beaklike protrusion in the middle. The masks have different expressions and different coloring. Her skin is black with two white arms stripes on each side and white circles down her chest. Her forearms are large, and have either spikes or tufts of fur sticking out at the elbows, and she has two triangular extensions on the back. It would appear that her body is intended to resemble a tailcoat.

The masks on her head are capable of detaching themselves from her and growing bodies of their own, which are capable of infinite reproduction over time. They do not appear to be intelligent, and do not have a soul of any kind, meaning that Alices can kill them without having to lose a reserve tank. They follow Giger's orders without speaking.

Human form
Giger is a tall young woman with light hair and dark eyes. She wears a ponytail, and her hair is combed to both side with a segment of bangs in the middle. She wears a long buttoned tailcoat with dark pants and boots, and appears to have no shirt under her tailcoat. Her eyelashes are defined, and she appears to be an attractive person.

As a young girl, her hairstyle was much the same, but was pulled into two buns with differently colored coverings, rather than a ponytail. She wore a dark shirt with stripes on the forearms and dark pants, and carried a doll that closely resembled the bodies and faces of the "parents" her mask creates.

As a teenager, her hair was longer and kept in a ponytail of sorts, while keeping the same bangs. It was held in the back by a black covering similar to the ones previously used to cover her hairbuns, and several long strands of hair stick out of the bottom. She wore a dark turtleneck with holes on the shoulders, a dark skirt, and dark boots.

Personality and Backstory
Giger longs most to have a family of her own. Before choosing her World Devil form, she is seen in a park, watching the passerby. After seeing a family walk by, she remarks that family is a nice thing - something she never knew, having grown up in the military. Afterwards, she emerges as a World Devil with three masks that are able to reproduce indefinitely, thus making an infinite number of "families". As thanks for giving her the inspiration for her body, she warns them to escape before destroying a nearby area. It seems Giger does not fear the Alices, nor does she refrain from giving them information. She says they are important specimens to her people, and seems to want to capture them rather than kill them. She also offers the chance to escape to everyone that she is not ordered to kill, and only attacks when they refuse to stand down. She explains her mission to Adachi and Azuma in an attempt to converse with them as two humans, and she rejects any statement that she is a monster, insisting that they recognize her humanity as well.

She grew up under the care of the King. In a flashback, she reveals that she didn't want to die, and thus, followed his orders so she might become strong. He teaches her to care for other people and despise conflicts, and respect all life and have mercy in her heart. Later he demands that she take the life of a prisoner. He tells her she needs to kill another to save herself. She protests, saying that even though they are different skin colors, he has a family too, and she can't build her happiness on the suffering of another family. He then tells her that the positive things he taught her were a lie, and she needs to embrace the darkness inside her as a weapon for the greater good. In her despair, she shoots the man, and he praises her, saying that in ten or twenty years she will receive her mission.

After accepting that Azuma is stronger than her, she stops fighting and tells them exactly how Maze and Zera came to be. Recalling that the King told her "For the greater good, you are allowed to take lives, if you are willing to bet your own life on it", she reverts her head back to its human form and shoots herself in the head. Her last words are "I really wanted it", but whether she wanted to achieve the greater good of the King or have a family is left unclear.

Abilities
Giger is on a much higher level than the previous World Devils, which is apparent from her not losing her mind upon becoming one. She easily chops off Adachi's leg when he attempts to take Azuma and run once she states that her mission is to kill every Alice she comes across, and dodges Seki's Servant Devil missiles with little effort. She can shoot beams out of her finger which possess massive power, and can materialize them into a staff of sorts, as she did when about to kill Azuma. She is also quite fast, as she managed to escape Masoto's and Scapp's grasp to kill Utou with a beam when Scapp teleported away a second before the transfer to Wonderland. While on Zera she is seemingly indestructible, in Wonderland her head begins to crack when being hit with Saeki's manifestation of Utou's corpse.

Giger's main ability is "Mother, Father, and Child". It's activated when the masks on her head detach, each becoming its own entity. As noted by Seshio, "Mother, Father, Child" is not a division of Giger's power among three, but rather a multiplication, with each the mother, father, and the child having power equal to Giger's own. When "Mother, Father, Child" is activated, however, Giger's body is left vulnerable with little to no power of her own, leaving her only able to watch. The trick with this ability is that as long as the "mother" and "father" still exist, there will be an infinite amount of "children". "Children" will grow up to become parents themselves, ultimately creating more "children". As said before, every single child and parent will have power equal to Giger's own originally, making this ability extremely dangerous. It's only defeated when Azuma appears where the other Alices have gathered, destroying them all with a giant axe in one fell swoop.