Asuha Tohara (塔原 明日葉, touhara asuha), originally named Asuhariet Ygvar (アスハリート・ユグヴァール) by her mother, and more commonly referred as Asuha (アスハ), is one of the main female protagonists of the series. Asuha is the daughter of Naoya and Mercelída and the true first princess of Ygvarland. She is Rotte's older half-sister.
While originally a normal human child, it is later revealed in advanced chapters of the manga that she is in fact half human / succubus after visiting the Dvergur Miraculous Spring that stimulated the growth of her succubus traits. Since her father is of incubus descent, it is possible that she might be a "purer" succubus than both her mother and sister since she is the daughter of an incubus, the original male counterpart of the succubus, which gives her the abilities of the succubi without their weakness.
Asuha looks more like her father than her mother. She has dark blue eyes and long hair but it was longer when she was a small toddler. Being part succubus, she also eventually gains her own pair of wings in the manga, but shows no signs of a tail.
Asuha was given to Naoya by Mercelída to take care of her claiming that she is their child when she was around 3 years old. Naoya accepted and took care of Asuha. Despite living in poverty she was happy to be with her father. Asuha believed her mother was dead at the time.
She is shown to be outspoken, hyper and friendly. She does jump into many actions without thinking of others, but she truly means well. She also has shown a disliking for underwear and will not wear it most of the time. This is due to her mother's heritage. In fact, her relaxed and unabashed attitude makes closer to a succubus than Rotte, even more notorious when she wears Rotte's most embarrassing clothes (gifts from her mother) without an issue and when she temporary becomes an adult thanks a device of Ini.
Asuha and Noaya have a very healthy father/daughter relationship, despite living in poverty. Asuha loves her father very deeply and loves to see him smile.
Despite not being aware of their situation, she and Rotte have a big sister/little sister relationship. During a conversation with her mother, Rotte states that she sees Asuha as an older sister; which is ironic since Asuha is her older sister.