Is this the manhwa that the boy got bullied by his classmates while the teacher teaching, ...

Is this the manhwa that the boy got bullied by his classmates while the teacher teaching, when the boy stand up and tell the teacher that he got bullied and all of his classmates laughing including the teacher. And teacher said "Why would i care?" And the boy got angry and he pulled he's weapon from his bag then he killed his teacher and all of his classmates