When You Open the Door, There Is a Monster There

Ordinary student Mogyeong receives a mysterious package from an unknown sender: inside is a longsword, followed by a text message saying, “You’ll need this soon, so be prepared.” Not long after, strange “doors” appear inside his home, and intruders with bizarre abilities break in, claiming they’re looking for “that guy’s bloodline” as they kidnap his mother. Chasing after them, Mogyeong discovers that he is a descendant of “immigrants” who crossed over from another world to Earth and that those doors connect to this other realm. Together with newly found allies, Mogyeong begins a desperate fight across worlds to rescue his mother from the monsters and factions that lurk beyond the doors.

Original Webtoon:
Naver Webtoon, Naver Series