In this world, there exist "normal" human beings and those with ears called "beasts." Beasts have a unique body that experiences heats/ruts and pregnancy between the same sex is possible. Akira Miyaji is a beast doctor. A beast himself, he defies nature to be one that is not swayed by instincts. Kijima is the hospital director who likes to meddle with Miyaji. Kijima, born with the rare dominant gene, has very strong pheromones which results in him leading a very crazy sex life. Miyaji, although not very good at dealing with the guy and in spite of being the total opposite of him, is tempted by him. One day, Miyaji is hit by Kijima’s pheromones which triggers an irregular heat in him...!?