Injak

From ilovemanhwa.com:

A HIDDEN WAR AROUND THE SECRET OF SEOUL, THE 600 YEAR OLD CAPITAL OF KOREA. Joo-hee never dreamed he would be investigated in the Presidential Residency by making emergency calls to see the flame from the city center though he felt wrong to know noone else witnessed the flame at school. People from National Fengshui Office said Seoul is in danger, for some people are breaking the seals on the places of bad chi. Indeed, people are killed by unearthly monsters, and not knowing what talent he has, Joo-hee's life is swept to this hidden war.