Help me find manga

Hello everyone I'm looking for a manga I read long ago, the things I remember are this

-Mc is a male, he becomes a sub teacher because the advisor is no good (but he turned leaf chapters later) the thing I remember the most is he beat up all the higher class as he heard that one of the class is getting up.

- the classmate is a chubby who uses a spear and he has a sister with glasses which is in the same class

- Mc is friends with majesty, majesty goes to the area and sees the bodies laying around all beaten up students

- if my mind is right the next plot is about the diary that the Mc read when he goes to a dorm

- one of the plots also is about 2 aristocrats that hide something that eventually gets to the newspaper

I tried Gemini it's no good It keeps suggesting me about the weakest crest but I know it's not that

Thank you for the answers in advance