The protagonist

A hero... 

1. a man of distinguished courage or ability, admired for his brave deeds and noble qualities.

2. a person who, in the opinion of the masses, has heroic qualities or has performed a heroic act and is regarded as a model or ideal.

A man of noble duty. A world's savior.

"Sigh... what a weird concept. Just strands of someone's imagination," he commented, after pondering over this for the past ten minutes.

He threw the dictionary aside.

"The world isn't some colorful place where someone will appear to solve all your problems and save those who are in need." He concluded.

It only happens in fantasy, and he never quite enjoyed those types of stories. So, he failed subsequently to connect with this book's antagonist.

"I prefer Astin over that childish kid after all."

Yes, in The Reincarnated Demon King novel, the antagonist was the hero.

Nonetheless, reading was his only pastime.