I'm No Fool, Even Though I Farm in the Apocalypse

Luo Er saved Hogwarts and the British Wizarding World in the Harry Potter universe, but before he could celebrate his victory with his friends, everything went black. Wait! Why does the pot of instant noodles in front of me look so familiar? Isn't this the same pot that made me transmigrate? I'm back? Before he could even enjoy his newfound life of doing nothing, his reborn sister told him that the world was about to be invaded by the demon realm, plunging it into an apocalypse. Now, on top of all the usual problems of survival, he has to deal with demons slipping through cracks between worlds and the bizarre dungeons they have designed. I... I want to go back! I haven't even enjoyed the fruits of victory! I bled for the Wizarding World! He thought the biggest advantage he had was the magic he learned at Hogwarts, until he awakened a supernatural ability... This is the story of an HP wizard leading Muggles in farming during the apocalypse, while fighting off an invasion from the demon realm, and perhaps even leading humanity in a counterattack. (Readers' group: 378622434)