Kimetsu no Yaiba: Katanakaji no Sato-hen

After inheriting the company from their parents, siblings Yuuhi and Yuamu Oudou have started to work at Ultraterrestrial Trouble Solutions, an organization that hunts aliens. Although they have never encountered aliens before, Yuuhi is desperate to meet one as he believes that an alien has stolen his important item called the "Earthdamar." One day, while searching for extraterrestrial creatures, Yuuhi and Yuamu find a strange spot in the forest where many trees have fallen, forming a scenery similar to a crop circle. As they venture further, they discover a mysterious spaceship and enter it out of curiosity. To their surprise, they come across Yudias Velgear, an alien from the Velgear Star Cluster. As it turns out, Yudias is seeking to learn about Rush Duel—a card game popular among elementary school students—as he believes that it will save his home from a long war. With the siblings agreeing to teach Yudias about Rush Duel, they eventually realize that their first contact with an alien may not be a random coincidence. [Written by MAL Rewrite]

Gol D. Roger was known as the "Pirate King," the strongest and most infamous being to have sailed the Grand Line. The capture and execution of Roger by the World Government brought a change throughout the world. His last words before his death revealed the existence of the greatest treasure in the world, One Piece. It was this revelation that brought about the Grand Age of Pirates, men who dreamed of finding One Piece—which promises an unlimited amount of riches and fame—and quite possibly the pinnacle of glory and the title of the Pirate King. Enter Monkey D. Luffy, a 17-year-old boy who defies your standard definition of a pirate. Rather than the popular persona of a wicked, hardened, toothless pirate ransacking villages for fun, Luffy's reason for being a pirate is one of pure wonder: the thought of an exciting adventure that leads him to intriguing people and ultimately, the promised treasure. Following in the footsteps of his childhood hero, Luffy and his crew travel across the Grand Line, experiencing crazy adventures, unveiling dark mysteries and battling strong enemies, all in order to reach the most coveted of all fortunes—One Piece. [Written by MAL Rewrite]