MTL - Little Mermaid Dressed As a Scientist - Chapter 5

The Immortal Path led to Longevity and Sovereign was heading in ease. When the Longevity was no longer in ease, all living beings were just prisoners. Conspiracy, internal strife, and the invasion of the others, all of it emerged together. 

In such a world, there was such a young man. He made his way upstream, stepping on blood, defying the emperor, destroying the various kings, and slaughtering his way through the hundred clans to form an Immortal Path towards the throne of Sovereign! The Immortal Path was endless, while the Sovereign was limited. He used his blood to forge his immortal legend.

- Description from Novelupdates

[No weak protagonist, No simp, Prodigies battle for supremacy, Explosively satisfying invincible (Overpowered) protagonist type]Jun Xiaoyao transmigrates to a Xuanhuan (mysterious fantasy) world, becoming the Divine Scion of an Ancient Aristocratic Family. He possesses an unbeatable background, world-shocking talent, and furthermore, obtains a sign-in system. At the very start, he signs in and receives a fully developed (Great Accomplishment) Ancient Sacred Body.Signing in at the Taiyue Ancient Stele, he obtains a six-star reward: the Divine Elephant's Prison-Suppressing Strength!Signing in at his ten-year-old banquet, he obtains a seven-star reward: the Supreme Bone!Signing in at the Bronze Immortal Palace, he obtains an eight-star reward: the Myriad Creatures Mother Qi Cauldron!Signing in at the Boundless Realm Sea, he obtains a ten-star reward: the Great Art of Transforming into Freedom!Countless years later, Jun Xiaoyao sits cross-legged in the Ninth Heaven, points his sword towards the Azure Sky and declares: “Across the Nine Heavens and Ten Earths, I control destiny! At the end of the Immortal Path, I am the Apex!”Novel Keywords: Opening with a Sign-in to an Ancient Sacred Body

Xia Lian, a 21st century military doctor died in an explosion and found herself transmigrated to the body a 12 year girl. Her mother died and her father abandoned her and her little brother for another woman.

“Host, you are about to load the sci-fi adventure system, please be prepared”
“Three Body”.
“Wandering Earth”.
“Interstellar”.
“Gravity”.
“Mars Rescue”.

Uh …
As the youngest full-time professor of mathematics in the history of Jiangcheng University, Pang Xuelin was a bit stressed.
Uh …
The hardest science fiction, the best times.

- Description from Qidian