Nishimiya Kouga is from a distinguished alpha family which puts severe importance on being purebred. At work, the person he acknowledges as his rival in business performance is Houjou Misaki, who is also an alpha. Kouga has been putting some distance from his alpha supremacist grandfather, the current head of the Nishimiya clan. But one day, on the latter's orders, the family butler, Harada, visited Kouga with a child. Haruto, the omega child, is a distant relative and Kouga has been ordered to care for him. Kouga, despite his disgust with how selfish alphas are, felt pity for the meek and frail-looking Haruto and reluctantly complied. Now, Kouga is struggling to take care of Haruto who to his surprise, turned out to be a really energetic boy. At the same time, Kouga found out that Houjou also sends his child to the same kindergarten that Haruto attends. And that's when he discovered a shocking truth about Houjou.