A1 Xingdong Yubei Zu

The newbie police officers Fang, Beagle, and Kroos were ordered to go to the slums of the Infected in the trading city of Tkaronto to do an internship. Although initially they had problems because of the crowdedness and other conflicts, they get accustomed to this and make friends with the Infected. While the end of their half-year internship, that would make them proper police officers, is nearing, a Catastrophe is quietly approaching the city of Tkaronto...

(Source: Official Site, translated)

Note: Chapter count includes one prologue and two bonus chapters.