In This Life, The Greatest Star In The Universe - Chapter 132:

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?

Senju clan ancestral hall, everyone: “I hope that the ancestors will bless me and make my Senju clan great again…”

But the protagonist stared at a photo in the ancestral hall: “Uzumaki Mito looks really good.”

~The personality of the crumbs in the crumbs was detected, “Grass Dungeon” was awakened, the mission goal… to make the Senju great again! Now start assigning you a great mission guide… Already assigned, Uzumaki Mito!

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With a few words, the protagonist carries the soul of Uzumaki Mito, and awakens the very grassy “Grass Dun”.

The magnificent Mrs. Hokage… In order to make the Senju clan great again, to protect Konoha and even the ninja world, and to prevent the protagonist from spoiling this world, I have broken my heart.

- Description from novelbuddy

The hero who was killed by the demon king ended up reincarnated as the son of the one who killed him! Thus began the life of the hero who donned in the mask of the ideal demon prince to topple his own kingdom while doing his best to prevent anyone from discovering his identity―― But to do that and blend into the demon tribe society, he had to kill his former comrades. Nevertheless, to become stronger, to save humanity, he had to walk through all kinds of paths of carnage! This is the tale of the demon race’s fake prince destroying his own kingdom.

O Hero, Trample Those Who You Should Protect!

TN: Most part of the other character in the novel is depicted from a non-human perspective so expect something that is completely different from the common sense of human.