Solo Leveling, Volume 6 of 15 (by Chugong)

Jinwoo continues to progress rapidly through the Demon’s 6 Castle, climbing toward the top floor with the help of a demon noble who has agreed to escort the intruder if it means not having to fight him herself! Preoccupied with his personal quest, Jinwoo is unaware of the escalating threat outside the dungeon. The ant magic beasts that laid waste to Jeju Island are looking to relocate, and if they reach the mainland, all of Korea could fall. Will the combined S-ranks of Japan and Korea be enough to quell the swarm―and will Jinwoo be joining them?!