The two have known each other for six years and been in a relationship for four.
They met at the university’s entrance ceremony.
He only looks like a delinquent.
After honing his own unique style, his appearance just happened to turn tough-looking.

Besides the usual male-female dynamic, humans also possess a second gender classification: Alpha, Beta, and Omega.

Alpha (α)

• Endowed with superior physical abilities and build
• Possesses pheromones
• Experiences regular heat cycles

Beta (β)

• Lacks the traits specific to Alpha and Omega
• Unaffected by pheromones
• Makes up the majority of the population

Omega (ω)

• Has a period of sexual arousal called "heat"
• Releases strong pheromones
• Reacts to Alpha's pheromones
• Can become pregnant and give birth regardless of gender

Heat
A periodic mating season experienced by Omegas.

Rat
A mating season experienced by Alphas.

Pheromone
A special scent emitted by Alphas and Omegas that influences the recipient's gender and secondary sex characteristics.

Pair (Couple)
A state in which an Alpha and an Omega share a special bond.

Fated Pair
An innate, one-of-a-kind pairing determined at birth, where both partners strongly respond to each other's pheromones.

Suppression Agent
A medication used to suppress heat, rat cycles, pheromones, and similar phenomena.

Nesting
The habit of Omegas gathering bedding, clothing, and other items to create a safe, secure space.

Marking
The act of leaving one's scent on others or places to indicate a personal connection.

Synopsis

One afternoon, you was suddenly overcome by intense nausea and fatigue. Thinking it couldn't possibly be true, they nevertheless took a pregnancy test—and the result came back positive.
Still skeptical, they kept it a secret from Yutaka that day and headed to the gynecologist the next morning. Inside their belly, a tiny life had taken root—

The two are living together.