The year 20XX progress in genetic technology...has created a world shared by human and "demi-beast" -half human and half animal.

The "heat" a sexual charistic patricular to demi-beast.I'ts effect are both physical and mental.. also both gender can get pregnant from a mate with their bond partner.

And place the demi-beast in a state where reproductive instict cannot be disobeyed. In order to prevent sexual crimes and trouble related to "heat".The use of supressant medicine has been compulsory.