The mark-MONSTER!

A group of young men in school uniforms stand in a hallway, with one in a red hoodie being pulled by another, while a blonde-haired boy watches from the foreground. The scene shifts to a boy and a girl eating at a table, then cuts to a man lying on his back as a hand drips a yellow liquid into his open mouth, followed by the boy in the red hoodie lying on a bed and then eating a piece of food while sitting against a wall.