The Sulky Catfish and the Modified Trousers

When I arrived at school, a man who looked like a sulky catfish was standing in front of the school gate. I tried to walk past him in silence, but the sulky catfish said, "Hey, you, wait a second."
I didn't even need to wonder who this guy was. The catfish was the teacher in charge of student guidance, so I knew he must be talking about my school trousers not meeting the dress code.
Sure enough, the sulky catfish said, "What are those trousers?"
Even if he asked what they were, I didn't know what he was asking about. When I told him the brand was "Yaban," he seemed at a loss for a comeback and just said, "Hmph." It was rude of a catfish to ask someone a question and then just say "hmph," but I knew that if I said anything about it, things would get even more troublesome, so I stayed silent and cracked my neck joints.
"Class and name."
"Class 1-5, Hyaku."
The catfish put a mark on the roster he was holding.
"Come to the student guidance office after school."
"..."
"Well?"
"Yeah."

In the classroom, Kaburagi was fuming with anger. Next to him, Yada looked gloomy. It seemed both of them had been caught by the catfish at the school gate.
After school, the three of us went to the student guidance office.
"Excuse me."
When we entered the room, the catfish looked over at us, looking annoyed. A dirty cup was sitting on his gray steel desk, filled with some kind of dark, murky liquid.
"Sit in those chairs."
He pointed to the folding chairs in the corner, still looking as if it were a huge bother.
I sat down as told, and he began his lecture with an even more annoyed expression. I thought if it was that much of a bother, he should just stop, but I knew he would definitely get angry if I said that. So, I focused my energy in my gut, held it in, and stayed silent.
As I let his words wash over me, the catfish got carried away and started saying something strange.
"Still, all three of you are from Class 5. Class 5 has a lot of rule-breakers, doesn't it?"
That wasn't true.
"Actually, it just happened that only Class 5 students were caught today; in reality, there are far more from Class 7 or Class 9."
The other two burst out laughing.
The catfish stayed silent and glared at me intensely.