The Prime Minister’s Darling - Chapter 440 - : 223 Couples (two more together as one)

The story is about a boy entering high school, who answers a strange call from a public phone one night. The caller challenges him to a bet: She’ll remove the birthmark which he sees as the cause of so many problems, and he’ll have fifty days to win the heart of a girl he’d considered far beyond his reach. And with this, a very strange summer begins.

Jiang Pengji got something called the Court Intrigue Stream System.
System: “Your goal is to become the most prestigious woman in the kingdom (the Queen)!”
Jiang Pengji: “Okay, System. No problem!”
Years later, she met the target by becoming the most prestigious woman (the Empress).
Jiang Pengji: “Well done, no?”

- Description from Novelupdates

As the owner of an ordinary bookstore, Ling PingAn’s biggest wish was to muddle through life and do absolutely nothing.

The Great Norther Wall. The Dragon Knights. The Lords of the Winter Mountains. The Descendants of the Primordial Dragon. These are the various titles of the Grand Ducal Clan Ragnar, which boasted a rich, thousand year history. Theo Ragnar resolved himself to aiming for the throne of that very same clan. ‘These cursed chains weren’t something I could slip out of. They were meant to be broken with strength.’