One Piece: Unreal Adventure - Chapter 10: Fighting Crabs?

When Fang Jin learned that he was in a cultivation novel where the protagonist was a lady and that he had become cannon fodder, he quickly racked his brain to think of a way to save himself.

Everything seemed wrong until he saw it.

[First day as a pet owner.]

[Attractiveness +1]

…

[A day of cultivation with zero gain.]

[Understanding +1]

Follow Chen Ming as he accepts disciples, establishes a sect, and fights his way in a world that deems him a cannon fodder.
He goes against any common sense using his wits and novel knowhow to finish missions and arm himself against his cruel fate.

- Description from Novelupdates

Tenjou Yuuya has been a bullied boy since the past.He lives in the home of his beloved grandfather while he goes to school. As usual, he receives a harsh bullying, and he takes an extended absence from school to have some time to heal his wounds.While on this long time of absence, he takes the opportunity to clean his grandfather’s house and goes to a room he never went before, where his grandfather keep many different objects that he gathered from his travels around the world. While he was arranging the objects, he found a door not on a wall among the objects.Out of curiosity he opens this door, what he found on the other side was…

The heck? l got reincarnated as a prince in another world!I have a system as well?[Choose class][Fiend Or Human Class?]Fiend Class.Choose the class from below.[Milf Manic][Blood Kin Copier][Plunder Sucker][10X Milk Man]Yeah I choose to become the strongest!On the other hand, why is my maid so cute?“My prince~ not there!”