Eroge: I can Travel To The Ancient World - Chapter 121: Lightning Investigation

Dumbledore always believed Voldemort was the greatest threat to the wizarding world until a thousand-year-old vampire showed up at Hogwarts with the deed in hand—“A thousand years have passed, and Hogwarts' lease is up!” said Dracula. “Headmaster, you wouldn't want your students to be homeless, would you?”“What do you want?” Dumbledore asked gravely.“Anything interesting.”“Well, I think the position of Defense Against the Dark Arts professor is quite interesting!”...And so, Hogwarts gained a professor who couldn’t be dismissed.McGonagall: “Albus, I don't think Professor Dracula's teaching is suitable for the poor children!”Dumbledore: “There's nothing I can do, no one can fire him.”...Draco: “My father is a governor, I'll have him get you fired!”Lucius slapped Draco on the head, “Mr. Dracula, Draco speaks without thinking. Please, don't fire the Board of Governors!”...This is the story of a vampire who lived too long and found amusement in the wizarding world out of sheer boredom.

Rhett never expected becoming king until he slayed an ice dragon out of self defense and fulfils an ancient dragon slayers prophecy which makes them to crown him as their king.Transported to a gloomy and medieval like world, he is faced with leading the dragon slayers, the weakest of slayers among other slayers - demon slayers, gargoyle slayers, ghost slayers and shadow slayers.But ruling isn't so glamorous as he had anticipated and he is instead a warrior, with a system like ability which he must level up by slaying Dragons.And to his disadvantage, the world he is his controlled by SLAYERIOUS, an unknown and unseen entity. But that won't stop Rhett, he intends on dominating his world and even daring to slay the strongest dragon still alive, ruieen.And who knows, he might just defeat SLAYERIOUS if he tries harder.[WSA 2025 ENTRY]

After traveling to the Tivat continent, Lin Mo became a jar merchant, and since then he has embarked on a journey of selling jars.

Lin Mo: “Let’s open a jar. Whether it’s the Eye of God or the magic weapon, you can buy everything you need. You may earn blood, but I will never lose!”

Ningguang: “As long as you sell unlimited quantities, I am willing to give you all the money, and people can also give it to you!”

Hu Tao: “Golden Emperor Fen Tianyan? Or only ranked fourth on the Yihuo list? I can’t imagine the Yihuo in front of me.”

Ke Qing: “Sword Twenty-Three? Hey, what kind of terrifying swordsmanship is this!”

Yae Godko: “Touch your tail more, can you sell me an extra jar?”

Ayaka Kamari: “How can this Zanpakutō, Xiu Baixue, be so strong!”

…..

A few years later, everyone in the entire Tivat continent was looking for the jar left by Lin Mo.

- Description from novelbuddy

Protagonist travels between different anime worlds to right wrongs and uncover his reason for being along the way.