I'm Just a Side Character, but I Became the Guardian of the Marquess Family's Heir

Synopsis

I should have died in the accident, but when I woke up, I found myself inside my favorite novel... To make matters worse, I'm just a side character?! According to the story, the duke and duchess have disappeared, and all the servants are about to be fired... I've made up my mind. I'm going to live as I please! Or so I thought. Somehow, I've ended up as the guardian of two orphaned twins?! This wasn't supposed to be my role, but how could I abandon them? Just as I resolved to take the twins on their journey...