Andou arrives at the club carrying a guitar to show off. After boasting about, he bets the guitar in a match with Chifuyu, but smashes the guitar in his own mistake. On his way home, he's so focused on his guitar that he forgets his bag in the clubroom and goes back to get it.
Though that's common in movies and manga.
هذا في الأفلام والمانجا فقط
Eso solo pasa en las películas y manga.
Eso solo pasa en las películas y en el manga.
On n’est pas dans
un film ni un manga.
Anche se è una cosa comune 
nei film e nei manga.
Mesmo sendo comum em filmes e mangás.