The Jeokun Mountains, the immediate border between the Demon Tribe and the Alien Federation. It is the final strategic point where training and actual combat take place simultaneously. The Federation forces are searching for the ten Transcendents revealed in the Book of Prophecy and reclaiming their lost territories, conducting repeated conscription and selection processes. However, more terrifying than the war with the Demon Tribe were the absurdities and harsh treatment of military life.(Source: Naver, translated)
— Description from AniList community (anilist.co).
