Dai Gyakusatsu wo Hikiokosu Last Boss, Wakiyaku no Watashi ga Shiawase ni Shimasu!

The Last Boss Who Causes a Great Massacre— In the world I was reincarnated into, my favorite character's life held tragedies that were never depicted in the game? This is the love story of a supporting noble lady who cherishes and protects her favorite character and a once-lonely former final boss who gradually opens his heart to her actions.