Transmigrated as side character, I will steal all the heroines - Chapter 15: Playing With Reiji

She is the Crown Prince’s fiancee, but on the night of their wedding, an edict was made and she was given off to marry the crippled and paralyzed God of War.

She, a modern hidden ghost leader of an organization which gathered insane prodigies proficient in the various differing skill-sets. Highly skilled in medicine and poison, executes covert assassinations, viewed as insane and demonic in the eyes of people of the world. Killed in an accident, and reborn into the body of a disfigured young girl.

What? Face disfigured, identity stolen? A return to the family dim and hopeless? Her identity can be given up, her family can be forgone, but as for the one who harmed her predecessor who inhabited this same body, if she didn’t at least make them scream in unimaginable agony and throw them into a state of wretchedness, how could she live up to her demonic reputation? Endless turmoil ensues and it’s a battle to dominate over all! See how she shook the world dressed in a suit of red, her sword up against the dominant powers that rocked the Heavens! Her name spread across the seas, shocking the earth!

- Description from Novelupdates

Madeline Celeste d'Aumont is the first daughter of Duke Aumont and Duchess Louise-Marie d'Aumont who has been engaged to the Second Prince of Pays Des Abrutis since she was a child. The Second Prince decided to marry a woman closer to his own age and broke off the engagement to Madeline who was left with a broken heart and a reputation as being an unwanted woman even before she was an adult. The Duke decided to help his daughter regain her confidence and reputation by sending her to the Academy de L'échec.

Ito Aoi was the son of a Kendo master who ran a dojo in downtown Tokyo. One day while crossing the street to get some Yakitori, Aoi was hit by a delivery truck and woke up as the trash first son of Duke Montfort, Guy de Montfort. Duke Montfort also sent his son to Academy de L'échec only Aoi instantly recognized that he was now living in the world of an Otome Game that his sister loved to play and talk about all the time. Aoi recognizes that Madeline is the villain from the game. Aoi also recalled his sister saying that Madeline was terrible in the game, but is she really?

The main character is reborn as a character from a game he played in his previous life. This character falls into ruin along with the villainess, spending the last of their years together. A man named Kururi Helan.