MTL - Proficiency Panel Right At The Beginning - Chapter 5 serial killer?

In the Province of the Nine Skies, far above the heavens, there exists Nine Galaxies of Astral Rivers made up of countless constellations interwoven together.

The Soaring Dragon Continent is a world of summons, you can only become strong if you become a summoner! Yue Yang, an average high school boy, was suddenly transported into this world. When he woke up, he was greeted with a lot of worried faces and found out that he had assumed another person’s identity. Turns out he’s the good-for-nothing third son of the Yue Family, who had just recently drowned himself because of a failed engagement. Unlike the third son of the Yue Family who was useless in summoning, Yue Yang succeeded in making a contract with a summoning grimoire on his first try, even when the other guy failed for the past fifteen years. Others would have a headache making contracts with beasts afterwards, but countless beasts tried to gain favour with Yue Yang instead, acting like a good kid before him.

As a man who had lived for 20 something years and had always considered himself as a straight man, he woke up one day and found himself possessed by a stupid and cute system. Moreover, it was a gong-shou cultivating system?! Let’s see how a shou with raised hackles evolves into a (pseudo)queen shou, incidentally with a story of a hidden loyal dog gong.

- Description from Novelupdates