Ada Clover is the older sister of Carl Clover and the daughter of Relius Clover. Due to an unfortunate experiment, she was turned into the Nox Nyctores, Nirvana.
Ada is Carl's older sister, and frequently doted on him when she was still human. Due to her affection, Carl idolized her, and frequently spoke highly of her to his friends at school (much to their amusement). One day, for reasons unknown, she agreed to become the subject of one of her father's experiments, but according to the story, there was a possiblity Ada was forced. As a result, her body was used by Relius Clover in the creation of the Nox Nyctores known as Nirvana. Unfortunately, Carl bore witness to this depraved experiment and now seeks out his father in order to get revenge. Nirvana follows him now as his partner and weapon, acting upon his commands and protecting him. Many of the characters recognize her in her form of Nirvana, though the meaning of that has been left unclear.
In spite of losing her humanity and essentially becoming a puppet, Ada displays an unusual amount of sentience as Nirvana. There are many times where she will act on her own, usually when Carl is in danger or to attack a dangerous adversary. For instance, when Carl first confronts Hazama during the events of Continuum Shift, she attacks him without provocation. She does the same to Noel in another scene, surprising Bang that she could move without Carl's will. She also seems to frequently converse with Carl, who is the only one who is able to hear her (although other characters have doubted this). At the end of Carl's True Story, she acts on her own again in a confrontation against her father, fleeing the battlefield with her brother and Litchi. This surprises Relius, who briefly acknowledges her as "Ada" rather than "Nirvana," having previously only referred to her as if she was a thing.
As Nirvana, Ada has short light blond hair and blank eyes, with a crack on her left eye. She wears a purple dress with a white collar, a purple hat with a golden ring, and separate sleeves.
When she was human, she had slightly long hair, and wore a navy dress with vertical light blue stripes.
Before becoming a doll, Ada was a kind, calm, and cheerful person. She was always very kind to her younger brother. After becoming a doll, she becomes lifeless, but even then, she shows unusually high sentience. Then said by Carl that she is very sensative about her looks, and in Carl's arcade when she and Carl encounter Hazama, she seem to have a grudge and hatred toward him.