Twenty-Third Century of the Old Calendar

On February 1, 2149, the near-Earth asteroid "Apophis" roared in and invaded the earth. When humans tried their best to finally destroy it into countless meteorite fragments, they thought they had escaped disaster, but the cosmic radiation brought by the meteorite fragments caused human beings around the world to suffer from organ failure and die. Human society on the surface has completely collapsed. Except for the shivering survivors hiding in shelters several kilometers underground, there is no trace of human activity on the entire earth. Human beings, once the largest overlord of the earth, are no longer alive. The spiritual wealth accumulated by human beings in their long and orderly development, such as culture, religion, art, etc., Is almost exhausted. As human society is completely isolated from the earth's surface and the starry sky, the old Gregorian calendar's guiding role in astronomy, climate, seasons, etc. No longer has any substantive significance in human life, and has only become a method of calculating time. People also call it the old calendar. ....... I am a sick alien orphan living underground after the catastrophe. My body is weak and my movements are slow. But my alien body will continue to evolve and become stronger after being inadvertently exposed to surface radiation. Can I protect my people from the swarming threats of a strange new world? Protect my beloved girl?