Forsaken Priest of the Hero's Party - Chapter 53: You are the Embodiment of Freedom

This is a story about a legend, of one that can never be forgotten.Summer, first time down the mountains in 16 years, after being raised by his 3 masters and Fairy sister.

Naofumi Iwatani, an uncharismatic Otaku who spends his days on games and manga, suddenly finds himself summoned to a parallel universe! He discovers he is one of four heroes equipped with legendary weapons and tasked with saving the world from its prophesied destruction.

As the Shield Hero, the weakest of the heroes, all is not as it seems. Naofumi is soon alone, penniless, and betrayed. With no one to turn to, and nowhere to run, he is left with only his shield. Now, Naofumi must rise to become the legendary Shield Hero and save the world!

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

“Finally, the owner has appeared. You read me.”The Archmage’s legacy, the Book of Truth.Binair Dalheim, a dropout of the Elfenbein Tower, accidentally discovers the Book of Truth.“I will awaken your magical talent. In return, complete me.”The dropout boy, whose dormant talent has been awakened, begins his journey to retrieve the Book of Truth as requested.