Infinite Dendrogram (Manga) Volume 4 by Sakon Kaidou

While walking the streets of Gideon, Ray encounters a band of hoodlums harassing a young woman. During the conflict he meets a flamboyant new ally named Hugo, and the two decide to co-operate in order to take down a nefarious criminal group known as the Gouz-Maise gang. But little did Ray know that this seemingly simple rescue mission would cement just how gruesome a reality the world of Infinite Dendrogram could become.