Mushoku Tensei: Reincarnated as a Beast Race - Chapter 17 - In the Eye of the Storm

Ash Flameheart, a young boy who aspired to be a Greatest Beastmaster Of All Time, was on the verge of death. Betrayed by the Hero’s party, they left him to die in the hands of the Demon King’s army.As his llife gently ebb away after he muttered his last word to the world.“Ahh, I wish I could fly, free as a bird, soaring through the skies and beyond.”After his untimely demise, his soul transmigrated into another world. The Immortal Beast Realm!An eternity later, Ash opened his eyes and found himself encased in a dark space.Beep![Beast Master System has been installed into a new host][Calibrating the Host…][Name: Ash Flameheart][Species: Heavenly Phoenix][Growth Stage: Hatchling Phoenix][Cultivation Arts: Heavenly Beast Taming Art | Feather Swords Gather Array (Not Not Yet Learned) | Eternal Blood Flames(Not Yet Learned) | Ten Thousands Faces Mantra(Not Yet Learned)]Survival of the fittest!Tame or be tamed. Kill or be Killed!

Klaus had spent his entire existence as a puppet, bound by the strings of fate. However, a miraculous turn of events granted him a fresh start. The remnants of his former constraints smoldered in the ashes of his past. Now, unshackled and determined, he resolved to forge his destiny according to his own desires. No one, not even a deity, would be spared if they dared obstruct his path. Klaus was ready to wield the sword of vengeance and carve his own fate in the annals of history.

In novels with a stud there is always a Senior Martial Brother like this:

In the early stages of the novel, his innate talent is high, his cultivation is good, his appearance is handsome, and he has an intelligent, cute younger Martial Sister as a fiancée.

In the middle stages of the novel, he is caught unprepared and defeated by a young disciple (the protagonist) in the sect who’s hardly remarkable at all. From then on, he falls from his godly altar and loses his brilliance. Even his young Martial Sister leaves him for someone else.

In the late stages of the novel, he continues to turn dark, going down the Demonic Path and becoming the major villainous boss. However, the protagonist still ruthlessly defeats him and his soul is eternally sealed.

Once Qin Mo opened his eyes, he discovered that he had become this Senior Martial Brother.

- Description from Novelupdates