Castle

"Castle," South Korea's omnipotent crime syndicate. One man returns to Korea in order to topple the absolute stronghold that is "Castle": Shin Kim, the Korean-born Russian killer named "Amur Tiger." He comes back to the crime-ridden city of Hoe-Am in accordance with the last will of his mentor, Min Sung Kang. Shin Kim and his comrades put their lives on the line as they head for the final showdown...

(Source: Naver, translated)

Note: Chapter count includes a prologue and an epilogue.