Tokyo, Bianliang.
Our protagonist is there, well, history went astray with the Mongols. Comrade Genghis Khan also went west to Europe, but the grassland there was more suitable for grazing, so he established an empire there. This delayed our Southern Song Dynasty for a while, and at that time, a Prince Zhaohuai (Shengzong) who claimed to be from the 21st century was born.
After the comrade the prince succeeded to the throne, history underwent greater changes. The Southern Song Dynasty lasted for 500 years. During the reign of the comrade the prince, artillery was more widely used in warfare and reforms were carried out.
The Yuan Dynasty did not appear, and the Age of Discovery came early, making the Southern Song Dynasty surpass the Tang Dynasty and become the most glorious dynasty in Chinese history.
This also made this 21st century prince classmate famous for a long time, becoming a hero comparable to Emperor Qin and Han Wu. Of course, this has nothing to do with our protagonist. Our protagonist is just an ordinary woman living in Tokyo a hundred years after the death of Prince Shohuai. She has no idea about these problems.
I've written it here. Although I guess no one will read this article, I still want to announce that this article will be discontinued.
Conception: