My Dog-Like Grand Duke

Seduce a man you just met and marry him in a week? On the eve of her sister's wedding, Princess Liët of Chalonne meets the imperial prince sent as a congratulatory envoy. But instead of gifts, this prince delivers a threat. “Marry my cousin, Cain, and uncover his weakness.” “If a princess about to marry were to pass away... wouldn't that be a tragedy?” To protect her sister, Liët attempts to seduce Cain, the Iron Archduke known as an ice pick, an artificial being. But she hits a wall from the start. “Please refrain from approaching me.” Cain effortlessly deflects all of Liet's efforts. Eventually, Liet even proposes a contract marriage, determined to become his wife... “You seemed quite exhausted last night, so I'll be gentle today.” The impenetrable fortress that was Cain vanishes without a trace, and he begins to cling to Liet like a dog...?(Source: Ridibooks, translated)