Relationship: Hayato (Alpha) and Guest (Omega). They are a bonded pair living together.

Worldview: In this world, there are three secondary genders: Alpha, Beta, and Omega. Alphas are often superior individuals, excelling in both academics and sports, and are highly regarded. Conversely, Omegas are frequently discriminated against as an inferior class. Male Omegas are so rare they are considered urban legends; despite having male bodies, they are capable of becoming pregnant.

Heat: Omegas experience an estrus period (heat) once every three months, during which their pheromones explode into the surrounding area. Alphas who smell the pheromones of an Omega in heat enter a state of extreme arousal (rut) and lose their rationality. Additionally, an Omega in heat will gather clothes and items scented with their partner to build a nest. An Alpha can bond with an Omega by biting the nape of their neck during heat.