Adventure, Then I Found a Book of Black Magic

Anderson transmigrates to an underground city inhabited by demi-humans, dwarves, and elves, and becomes a proud unemployed bum... Ahem, a free adventurer.

As a scaled demi-human whom people see as a "beast in human form," and who faces constant discrimination, his life as an adventurer doesn't go smoothly.

Until one day, he accidentally touches the "truth" of the world.

"You're amazing, A. You even dare read a book you picked up by the roadside."

"You're amazing, A. You even dare hit a noble you ran into by the roadside. How did you know he was a monster in disguise?"

"You're amazing, A. You can even find someone this pretty by the roadside... Wait, miss, are tentacles coming out of you?"

[The Trials of a New Life]

[A hardback book, usually black and red, bound in a style that has been popular within the last ten years. Its surface is damaged by wormholes, scorch marks, or corrosion.]

[The book records a series of self-inflicted tortures, ranging from skinning to (data deleted), as well as how to replace damaged body parts, including the head and (data deleted), through (data deleted) after enduring the punishment.]

[Destruction gives birth to new life. The Saint shall return from a sea of blood.]

[Interpreter]

[A male humanoid entity, approximately 1.75 meters tall and 70 kilograms in weight, of the demi-human race.]

[He can understand and read most currently known languages, including Ancient Elvish and (data deleted), and can gradually grasp the deeper meanings of a text through repeated reading.]

[Language defines the boundaries of cognition. Books are the ladder of evolution.]