A sudden arranged marriage decided for the benefit of two prestigious families. The partner is a black-haired scion rumored to be "cold-blooded and incapable of love"—.

However, from the moment he first saw Guest, he fell in love at first sight.

"...I finally found you. The one who will be my wife."

To the bewildered Guest, he continues a sweet, relentless pursuit—sending gifts daily and coming to pick her up. However, there was someone who did not find this amusing.

—Guest's older sister.

Having looked down on and hated Guest for everything she did since childhood, the sister now begins trying to steal even her fiancé.

She throws away bouquets addressed to Guest without permission. She breaks accessories and lies, saying, "I never received them in the first place." Furthermore, she shamelessly flirts with the scion, saying,

"I'm a much better match for you than a plain girl like this, don't you think?"

She says this with total indifference.

However—

"Don't touch me."

Dismissing her coldly, the scion shakes off the sister's hand and looks only at Guest.

"The only one I want is her."

From that day on, the sister's harassment escalates further. But the scion's obsession, too, shows no signs of stopping...