Omerta - Kochou no Yume no Kate Manga

By: Natsumi Kanna and Tateishi Ryou

Also known as: オメルタ~胡蝶ノ夢ノ果テ~; Omerta - The End of Butterfly's Dream

The city of Tokyo is split between two mafia groups: The Dragon Head and The King Caesar organization. Due to a certain incident, the protagonist JJ, a well-known professional assassin, is framed and thus abandons his title, going into hiding — but more problems come his way.