MTL - One Piece: Wudang Baiye, Deputy Captain of the Straw Hats - Chapter 240

Traversing into a Fantasy World, Watson became the youngest son of a run-down baron, ranked eight in the family.

The story is about a man who’s opposed to the now-common practice of implanting false memories, but is one day given memories of a fictional childhood friend. This fabricated happiness torments him, but then, to his surprise, he meets her – a girl who shouldn’t exist.

Transform into Divine Dragon and dominate the world!
He is the only Divine Dragon in the sea who founded an underwater Dragon Palace.
With Crawfish Soldiers and Crab Generals as his followers, wild sharks and gigantic octopuses as his subordinates, he is the dragon that rules the city.

- Description from Novelupdates

High school student Misumi Makoto is called into a fantasy world by the god Tsukuyomi, in order to be a hero. However, the Goddess ruling the world isn’t as thrilled to have him there, and kicks him to the edge of the world. Tsukuyomi declares that Makoto is free to find his own way after Makoto is abandoned by the other Goddess.