Mononoke Hime (Dub)

A big dream and a young man determined to change the status quo and work hard to create a new world. The rare and precious treasures, the martial arts, and the lost strong caves, in this era of genius, full of challenges and opportunities. See the adventure of how the Lord lost the mainland and became the supreme Emperor of the storm. The former enemy, now, will never let go! The regret in the dream, now, must make up! When the spirit sword shouts, the heavens and the earth, I am the supreme! (Source: Anilist)

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]