After Humanity Loses the Ability to Reproduce

"""Although this book is short, it is neither poorly concluded nor abandoned—it has reached a proper ending. It is a thrilling and complete sci-fi story, and I look forward to everyone's appreciation!!! Sixty years ago, a catastrophe of still-unknown origin caused the entire world's population to lose the ability to reproduce. Now, sixty years later, the global population has dwindled to just one billion. Apart from the very few young people like us, born through the 'Spring Thunder Project,' everyone else is over 60 years old. Everyone keeps telling me that the fact no one was directly killed is already the greatest mercy shown by the unknown entity behind this catastrophe toward human c...