Forcefully, I Became the Duke's Fiancée

I was just your average run-of-the-mill young woman reading my favorite web novel entitled "Cania" When I woke up, I realized that I was trapped a beautiful girl's body named Raina, an unfortunate side characters are destined to die. I, who decided to get out from this story and wished to have peaceful life, suddenly proposed by one of the main characters who are still on underage. No, that's not the problem! Me? A side character? What kind of development plot is this?! ***Note:** This is a Best Challenge webtoon, it's not serialized, the english isn't official as the author is the one translating not LINE Webtoon*