In the desperate struggle for survival in a post-apocalyptic world, everyone has awakened to a unique ability known as 'Lexicon'! Zhao, who has been searching for his adopted sister, finally awakens the world's only radiant-level growable Lexicon on his 16th birthday after constantly hiding and evading danger. However, the true face of this world's hardship begins to reveal itself to him... Will he be able to grow successfully and find his sister?