Yu-Gi-Oh! Go Rush!!

Yuhi Ohdo and Yuamu Ohdo are elementary schooler twins living in Mutsuba Town who are in charge of the alien extermination company UTS (Ultraterrestrial Trouble Solutions). They spend their days working really hard searching for aliens using a mysterious device created by Yuhi... that is, until one fateful day!! Right after they created a mystery school club, they finally found a real spaceship and inside of it, they made contact with Yudias, an alien from the distant Velgear Star Cluster. Yudias has come to Earth, after he and his comrades were chased from his native star cluster, seeking a way to a new future, which "Rush Duel" seems like it might offer a means to do so, but knows nothing about it. Yuhi challenges the newbie Yudias to a Rush Duel in order to give him a helping hand. This is first contact between elementary school students and aliens, via Rush Duel! Now it's time to enter the new stage of Rush Duel introduced by this alien soldier from the far ends of the galaxy! Let's go, Go Rush!! (Source: Yu-Gi-Oh! Wikia)