In the desperate struggle for survival in a post-apocalyptic world, all humans awakened a special ability known as “lexicon.” Zhao Cheng, who has been searching for his adopted sister by hiding himself from place to place, finally awakens the world's only diamond-rank growable lexicon on the day he turns sixteen! However, the reality of the hardships in this world begins to unveil before his eyes... Will Zhao Cheng be able to grow stronger and find his sister?