In scott pilgrim world and traveling to other worlds with a system - Chapter 66 - Danny phantom world

This is an Isekai styled story, written from the point of view of the protagonist.

Discover the secret of the new, unknown world with Peter, as he sets his first steps in an empty, ruined city. Meet new people from all around the globe. Fight, laugh, and cry.

“The war is finally over?! Then, what am I going to do with my life?” Caedrel, a man who had spent his entire life fighting, had no idea what to do next. Fortunately, he was offered to become a teacher in the greatest academy in the world. However, he wouldn’t be a normal teacher but a spy for his country’s Emperor! Doesn’t sound too bad, right? Well, it would have been great, that is…until he learned that his class was for the most talented(weird) students in the entire world.

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?

A tree of 10,000 flowers, the world is the door.
The spells change a lot, but the hearts of the people are unchanged.

- Description from Uukanshu translation