Diabolik Relationship

The story is about a girl and her childhood friend Reiji.

She comes up to the manor of the Sakamaki family and sees that things have changed a lot over the years, along with Reiji's attitude.

She begs him to kill her but instead he keeps her at the manor where he tortures her and feeds on her blood. When asked the reason for her sudden wanting she simply says that she is sick of everything and since she was dying, why not make things faster by being killed by the person who saved her in the first place.

As time passes, Reiji finds out of a promise they made long ago and they both realize that the more they spend time with each other, the deeper they fall in love with the other.

How will they overcome the circumstances they will face in the future?