Mangas

MURDER LOCK - SCHOOL OF THE XXXXXXX -  Murder Lock: Satsujinki no Kyoushitsu -  Головорезы под замком: школа для убийц -  マーダーロック-殺人鬼の凶室
Kotaro Kudo was known as the "Streets' Strongest". Once, 13 thugs, thirsty for revenge, kidnapped his younger sister Hinami. Kotaro beat everyone, and on the same night, he was arrested on suspicion of murder, as each of them was later found dead. He is then forcefully enrolled to a certain school, in which all students must meet "a special criteria" to enter...[hr]