Aphorism

Aphorism (アホリズム) is a manga written and illustrated by Kujo Karuna. It was serialized Gangan Online from May 18, 2010 to January 28, 2016. It is complete in fourteen volume. Yen Press has licensed it for digital release in English.

Plot
Naraka High School is a seemingly normal school. However, unknown to the public is the cruel truth of what really goes on in the school's halls. Rather than studying, students are forced to struggle for their very survival. And the strong bonds of friendship may be the only difference between life and death.