F-Rank Lizard:Apocalypse Overlord

A bullied college student wakes up as a useless F-rank lizard, abandoned to die by his cruel heiress master. Armed with a devour-to-evolve system and 40 days until the apocalypse, he eats his way from runt to S-rank dragon, settles the score, exposes a conspiracy, and faces one last choice: go home, or save the world that threw him away.