In a post-apocalyptic world where enigmatic towers are humanity's final haven, those who ascend to the upper levels are worshipped as 'Astras.' Baek Homin, a mere underling, receives a transformative tattoo imbued with skills, granting him access to the memories of his three previous Astras selves. Empowered with this newfound knowledge, Homin embarks on a perilous journey, facing formidable adversaries. Can the Astras shield him from harm in this daring escapade?