Why Is Everyone in My World a Problematic Young Person?

In the world of Li Mingzhe, a genius illustrator who absolutely adores flat-chested girls, why is everyone around him such a walking bundle of problems? First, there is Chen Xinyao, a junior beauty and artist who keeps throwing herself at him. Then, during summer vacation, he meets Hagiwara Tsumugi, a flat-chested girl from five hundred years ago. In the new semester, he also encounters his ultimate siscon buddy, the hugely popular light novel author Lin Jingtang. Everyone Li Mingzhe meets has a serious problem.

"Could it be... that everyone in my world is a walking bundle of problems?!"

And among them is a great unsolved mystery: Hagiwara Tsumugi, the girl who has lived for a hundred years.