My Space-Time System - Chapter 617 Dead weight.

Lin Xiao was an orphan who strived to get stronger while living with his sickly younger brother in an unnamed small village.

Riku Barusak is a hard-working child. Despite possessing an innate superior physical strength and having withstood harsh training she fails to unlock her talent as a spiritualist. The failure results in her being thrown away by her family.

Abandoned, the only ones that extended a hand to her were the demons, the greatest enemies of the human race. Serving under them as a soldier she becomes a weapon of human slaughter, a fiend that should never have existed.

Transform into Divine Dragon and dominate the world!
He is the only Divine Dragon in the sea who founded an underwater Dragon Palace.
With Crawfish Soldiers and Crab Generals as his followers, wild sharks and gigantic octopuses as his subordinates, he is the dragon that rules the city.

- Description from Novelupdates

Sa Bina was on her way to write her SAT when she suddenly finds herself in a strange world. She is sent to be the old emperor’s concubine, but on their wedding night, the emperor gets murdered by no one other than his own son and the heir! To survive, Bina makes a deal with beautiful but deadly Lucretius and her life in this dangerous kingdom begins.