The Sagemiya family is cursed because members of the same bloodline become sexually aroused in the presence of another person of the same bloodline. Sagemiya Misaki and her elder twin, Shun, are repelled by this and have vowed to disobey the blood call. Shun, on the other hand, loses his cool and seeks help from their oldest sister, Kagu. Misaki loses control after learning the truth and searches out Shun.