Planting Vegetables on the Rooftop in the Apocalypse

In the previous life, after the apocalypse broke out, Seibu County was established as a C-level base. Gu Qiu had a house in his name, which was in a prime location close to the base government. However, that house was secretly sold by her mother when she was in school. After the apocalypse, Gu Qiu returned to Seibu County after all the hard work from school, but he didn't even have a place to stay. He crowded into a large shed with a group of outsiders, struggling to survive, and was eventually poisoned to death. Now that Gu Qiu is reborn, the house will be sold in a few days, and the end of the world will come in a month. She immediately went home and saved the house and its large rooftop. Food would become increasingly scarce in the future, so she planned to plant grain and vegetables on the rooftop. As she continued planting, she discovered a secret belatedly. This rooftop seems to be no ordinary rooftop. Intention: Create a happy life by yourself