My Happy Ending Plan as a Side Character – I Refuse the Villainess’s Bad Ending!

Reborn into the world of a romance novel, Shiho Morimoto now finds herself as Selnia, a minor character destined for an early grave. But she holds a secret: she knows the exact path to ruin that leads to the villainess and her twin brother to their doom. Fate has decreed their downfall, but Selnia refuses to accept a tragedy. To rewrite the destiny of an entire bloodline, she must transform the twins into beacons of light before the darkness consumes them. Can she defy the plot and secure a happy ending for all? Dive into the chapter 1 now!