Ingyaku no Gakuen ~Waida ni Habikoru Fukushuu no Wana~

"Let me go!! I want to die! I need to die!"
The protagonist, Tokorozawa Kouka, wrestled with a girl on the rooftop, trying to stop her from jumping.
"What happened?! Tell me!"
Kouka held the girl—Nakai Yuri—tightly as he demanded an explanation.
Yuri had been enduring relentless sexual bullying from two classmates, Higashifushimi Sumire and Nomaguchi Akira. The torment had driven her to attempt suicide.
Furious at the severity of the bullying, Kouka reported it to their homeroom teacher, Nogata Kaede. But the response was dismissive:
"Student issues should be resolved among students."
Worse, Kouka himself became a target of suspicion.
"Isn’t Tokorozawa Kouka the one bullying her?"
The student council president, Saginomiya Ayame, accused him, and Kouka was unfairly suspended.
With neither the teachers nor the student council on his side, Kouka felt cornered. But instead of giving up, he decided to fight back.
Revenge was the only way.

[Translated from dlsite]