MTL - Best Actor - Chapter 15 Did you give up?

High school student Mikoshiba Ryouma was summoned to a different world in the middle of a war. Sensing the malice from the one who summoned him (a summoner of the O’ltormea empire), he uses his martial arts to run away, killing important people of the empire during his escape. After the escape, he rescues two twin sisters from the hands of thieves. The sisters who can use magic, swear to serve him as subordinates. Thus, Ryouma begins his journey on the path of the supreme ruler.

The formless ancient world was infested with despicable demons. They hunted and feasted on mankind, keeping the human civilization constantly in a weak and suppressed state.

During the first known year, a magical mountain descended into the world from the realm of the Gods. Carved on this enormous mountain was a message: ‘Heaven Prevails’…

After the Grand Descent, a name that was given to the descending of the mountain, the Three Great Sages made their ways to Mystic Mountain where they learned to harvest what we now call magic, establishing the Mystic Cults and eighty-one sacred shrines to help aid mankind with the cult’s mystic powers against the eternal fight to the death with demons.

- Description from Novelupdates

In the vampire-ruled kingdom of Mildelar, the Blood Games stand as the ultimate form of entertainment—savage battles between familiars, humans bound to their vampire masters through blood pacts. Far more than mere spectacles, these brutal fights determine the prestige of noble families, shaping their power and influence across the realm. Lyon, a young human saved from death by a blood pact with the alluring Arya Valakys—one of the king’s daughters—is unwillingly thrust into this cruel world. Bound to his mistress, he is forced into relentless battles to elevate her standing.Lyon, however, stands apart from other familiars. While they derive their strength from the fear of punishment, he draws his... from having dirty thoughts about his mistress!

Two heroes of the game Legend of Heroes 2 who were rotten waters*.