From MangaHelpers:
An average of 260 humans are born every minute. On the 9th minute of the 9th hour of September 9, 2024, only 18 individuals were born. On that day and minute, 18 stars shined brightly in the sky, and these 18 children were chosen by prophecy to be the saviors of mankind. Nitarazu Hisoka wakes up, completely naked and surrounded by cold metal. Others lay around him, all approximately similar in age. As they attempt to grasp their situation, they find themselves face to face with the leader of a cult-like religious group known as "Kreetha." The explanation they receive from this religious group shatters any hope for a normal life for these young individuals. Now, they must survive the trials laid before them, while coming face to face with each others' pasts.