Manga/Anime name: Tomodachi Game
Plot:
Somebody is a traitor. Someone stole their school trip money and used it to become one of the participants of the game called Tomodachi Game. Katagiri Yuiichi is a sinister, sadistic, evil person who manipulated every participants just to destroy the game. 4 of his friends was the manipulator.
Spoiler: In the end, everyone was the traitor. All they just wanted was to win and survive the death game. The manga is now on its final stage. The creator of this game was none other than Katagiri Yuiichi.
Genre: School, Psychological, Dark, Disturbing, Profanity, Gore(in the last game)