Yagami Keiko

About
Keiko is a live-in nurse who is there to take care of Tsuchiya Kuon and also takes care of his sister, Tsuchiya Sera. She hopes to convince Kuon to stay at the hospital so he can be treated properly.

Her past is quite similar the the three orphans of Tsuchiya Wakako. Her parents died in an accident when she was 10. She was sent to a Christian orphanage and raised by the priest there, her surname comes from him.

She had a boyfriend when she was 15, he was a college student who was 4 years older than her. He became part of a Japanese NGO and got sent to a refugee camp in a country torn by civil war. He died shortly after. This made Keiko attempt suicide, but she failed. All of this made her decide she should become a nurse.

Her events tend to take place after Kuon suffers from his illness. She helps him and tries to convince him to go to hospital. Kuon seems to particularly dislike her angelic behaviour and he wants to break her by humiliating her. He gets Sei to look into her past to find something worth using. Kuon can either decide to send her away or see how far he can humiliate her with the promise to do so.

Part of these humiliations is forcing her to engage in sex with her younger orphan brother who is in love with her. He invites Yagami Tadashi and gives him a drink laced with an aphrodisiac. Keiko then has sex with him to ease his suffering as Kuon enjoys the scene. This particularly hurts Keiko. She tells him to do whatever he wants to her, but to leave out anyone she holds dear.

Depending on what is done through her route, she seems to want to help Kuon not just as a nurse, but as a woman. In this route she manages to melt his icy heart and get him to a sanatorium where he can recuperate with her by his side. Her other end has her just give up and leave for her own sake. A joke end has her rebuild Kuon into a cyborg so they can find evil.