MTL - One Piece: The Soul Purchasing Pirate - Chapter 857 Seven kings

Sing the story, bard, of the Firebrand. He, the youth who saved Morcaster from ruin. He, the warrior who defeated an empire. He, the archmage who crossed the Netherworld...The tale of Martel the mage, from his humble beginnings as a hapless novice at a magic school. Slow, character-focused and light-hearted progression fantasy. Updates daily.

Eren Idril died as an old, decrepit, and piss-poor adventurer by the maws of a D-Rank monster. He had a lot of unfulfilled dreams and desires that couldn't see the light of the day after the light in his own eyes died down.

But fortunately for him and unfortunately for the world, that wasn't his end. Eren was somehow dived back in time when he was a mere teen, attending Lionheart Academy for adventurers.

When life gives him a second chance, Eren decides to exploit it to its fullest. Experience his vile deeds as he partakes in them without feeling the slightest bit of hesitation.

Hiding in the Cold Palace and eventually becoming a Boss of Sorts. Li Mu was transported to a fantastical world and became a measly eunuch of the State of Xia. Despite having initially thought that his life would be a miserable one, he had unexpectedly acquired a check-in system.

I’ve had enough of being transmigrated into books.