Rebirth: A Cat with a System - Chapter 42 Combat Training!

Kurono Maou is a high school student who is sensitive of his sharp eyes and bad expression. No girlfriend but gifted with friends in his own way, he had been living a peaceful life.

Arthur finds himself reincarnated as a spider in a dungeon after discovering his magical skills in a world of magic and mystery. He knows that everything in this world can evolve into something greater. Arthur begins his journey to evolve himself into a human by conquering one of the most powerful and mysterious dungeons.As he starts his journey, he finds new allies and enemies who look different from him—some who become like brothers and others who may betray him.Finding himself at the center of world politics, Arthur somehow creates his own monstrous kingdom from scratch, determined to live the life he wants and protect the people he loves. In his kingdom, he needs not only power but also strategy, as gods, demons, and other races use their own tactics and powers beyond imagination to maintain control and conquer worlds. Arthur embarks on his journey to live the life he desires... but will he succeed?

Master martial artists were beings that no one can obstruct. A martial arts expert has been reborn into the body of a genius whose cultivation has been abolished and has been abandoned by a woman. Therefore, he starts cultivating the art of Xing Yi Quan, producing a solar system within his dantian. His innate talent tramples over all the geniuses, and even the geniuses among geniuses.

His powerful spirit and ruthless and ambitious nature, no matter who he is reborn into, will never change! Slaughter is instinctive, being cold-blooded is his personality, exterminating an entire family is only a means towards a goal, cruelty means infamy, and chasing after women… is just an interest.

- Description from Novelupdates

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.