Bokutachi ga Yarimashita

Although satisfied with his average lifestyle, Tobio Masubuchi wishes for a long and fun existence, hoping that nothing will get in his way. Alongside his good friends Sho Isami, Yuki "Maru" Maruyama, and Hidero "Paisen" Kosaka, the group passes each day worry free, doing as they please. But when delinquents from a neighboring school overhear Maru saying that they should die, their troubles begin.

After being kidnapped and brutally assaulted, Maru is found by his friends, who are shocked to see what has been done to him. Angry, Tobio proposes that they take immediate revenge, and after deciding how they should do so, the four put their plan into action. But when what should have been just a prank turns deadly, Tobio's aspirations for an undisturbed life are shattered forever.

(Source: MAL Rewrite)