My Little Sister Is Splitting Infinitely and the World Is in Danger

One morning, when I woke up, my younger sister had split into two. Before I could investigate the cause, my sister—Ai—started doubling in number every day from that point on. I ran around trying to return her to normal, but every day passed without any results… Until finally, on the fourth day, something unusual happened. On that day, a new Ai was born—different from the cheerful Ai I knew. She was quiet and exceptionally intelligent, known as “the 16th Ai.” She claims that she holds the key to stopping the splitting. However, while we strategize, the situation continues to spiral in a worse direction… ?