It's said that the people in this world have evolved from their cat ancestors.
Both males and females can give birth.

Grim Manabe's a minor radio personality.
He reluctantly accepts an invitation from his roommate to go out for drinks one night, where they're joined by a veritable litter of up-and-coming stars.
One of which, Masachika, turns out to be a fan of Grim's radio show and voice. Grim's apprehensive at first, but Masachika knows how to keep a comfortable distance.
The two gradually become closer and closer.

One night, Grim passes out while drinking alone with Masachika.
He wakes up to find himself shockingly in bed with the young man!