Yua is a third-year student at Suimei Academy who seems to be stalking Takumi but later befriends him. She, like Takumi, is an otaku and likes the Blood Tune animation.
Yua's twin sister Mia died in the first New Gene incident, and because of her parents denial of ever having Mia as their daughter in the first place and the mysterious circumstances of her sister's suicide, she decides to investigate independently the New Gene murders, even suspecting Takumi of having multiple personality disorder and being the true culprit of the incidents.
In truth, Yua felt guilty over her younger sister's death because she was always spoiled while her sister was jealous over the attention she got from their parents. Even being not sure herself if she was the younger sister and had killed and taken the older's identity to have their parents' love. She confronts a delusion who looks like Mia and awake her powers as a Gigalomaniac.
She apologizes to Takumi of suspecting him, and got his figures as he prepares to destroy Noah II.
