Seduce a man you’ve just met and marry him within a week?

On the eve of her sister’s wedding, Riette, the princess of Sharlone, meets the imperial prince who has come as a congratulatory envoy.
But instead of bringing a gift, the prince delivers a threat.

“Marry my cousin, Kain, and dig up his weaknesses.”
“If a princess about to be married were to die… wouldn’t that be a tragedy?”

To protect her sister, Riette sets out to seduce Kain—the Iron Grand Duke, known as an ice pick and an artificial human—only to hit a wall from the very start.

“Please refrain from approaching me.”

Kain coldly rejects every one of Riette’s advances.
In the end, she even proposes a contract marriage, determined to become his wife.

“You seemed to have had a rather exhausting night, so today I’ll be gentle.”

The impenetrable, fortress-like Kain is nowhere to be found—
and instead, he begins clinging to Riette… like a dog?