Berserker Mob Destroys the Main Story Unknowingly

Albert, the youngest son of the remote noble Falconer family, has a secret - he's a reincarnator from another world. One day, at the age of 14, he realizes that his present life resembles a game he once played in a previous life. However, his memory of that game is vague. Moreover, he was a mob whose name didn't even appear in the game. Al begins to question the meaning of his own existence, and enrolls in the Radford Royal Institute of Martial Arts, where the main game takes place!