Transmigration: Starting with a Tsundere Little Sister

[Cthulhu + Foundation + No Heroine + Madness + No System]

In ancient times, people discovered that combining different genes and bloodlines could create people with different traits and abilities. From then on, the world entered a new age, and all kinds of genetic lineages began to emerge.

The protagonist, Li Feng, sees someone drowning and rushes into the water to save them. He manages to pull the person to safety, but runs out of strength and sinks into a deep sleep in the water, transmigrating to this world.

After arriving in this world, Li Feng discovers that he has a younger sister no one else can see.

Many people say Li Feng is sick. But is the protagonist the one who's ill, or is it this world?