Chisato Hasegawa is the school nurse of Hijirigasaka Academy and a magic user and acts as Basara's mentor. She is one of the main characters of the series.
Chisato is a woman with a voluptuous figure with breasts even bigger than Mio's. She has hip-length, dark brown hair, red glasses and a 'beauty mark' under her left eye. The nurse usually adorns a green sweater with a white robe on top, a short skirt and long stockings.
She is a wise, caring person shrouded in mystery. Chisato embraces advances made by Basara and may at times take the initiative herself.
Around 15 years ago, Basara's mother died while giving birth to him. This immediately led Chisato to become defensive of him.
Chisato brings Basara home with her, where they have extremely intimate sessions, ultimately leading to Basara losing consciousness. In the following days, Chisato would become more aggressive in her approach with Basara, earning the latter to be a point of envy from many people within the school. Later, Sakazaki would warn Basara of her, and advise him to stay away from her as she couldn't be trusted, as she was just too good and had a large influence on the school.
Later on in the Volume, when Tachibana and Dojo attack Basara, she would trap Mio and Yuki inside a barrier in the infirmary. Basara would beg her to open it, but she refused. Sakazaki would come to attack, angering her. Not long after, Sakazaki would attempt to betray Basara, and would succeed in cutting off his right arm, which was holding Brynhildr, causing Basara to enter a berserk state. Chisato would stop him right before he could kill Sazaki and would explain that Brynhildr's soul was in a weakened state and could not exist without Basara as its master. Chisato would then explain that Sakazaki is an Angel named Ornish. Apparently he was jealous of Basara after the "bonding" that happened at her house in the days prior to the incident. This was not the real Sakazaki in other words, just a fake. Chisato knew this but did not bother either way.
Ornish would then stand up and continue to praise Chisato while putting down Basara. He claimed that she was a Goddess and that no lowly human could touch her, especially not a cursed creature who had three different kind of bloods inside him. This infuriated Chisato to new heights, as he insulted the very existence of the only remaining thing from her dead sister. Chisato would explain that 15 years ago, she swore to protect Basara after her sister's death. She would also explain that she was always protecting Basara from behind the scenes, like the kiss in Volume II, which helped Basara awaken from Yuki's sleeping spell. Along with the bandage in Volume III, which acted as a charm to protect him from Maria and Zolgear's magic. Chisato would then kill Ornish with no remorse, and calm down Brynhildr. While carrying an unconscious Basara back, she remarked that she couldn't reveal her real self yet, or the fact that Basara had two mothers.
Abilities & Powers
She is an extremely powerful Angel, having the ability to instantly kill Ornish, even while having a large portion of her power sealed. Along those lines, she seems to be an expert at sealing and making barriers.
Basara is Chisato's protege and nephew. She is deeply in love with him.