Yuu Gi Ou: Go Rush!!

Yuuhi and Yuamu Oudou, siblings who inherited their parents' company, Ultraterrestrial Trouble Solutions, are tasked with hunting aliens. Their company's mission leads them to a mysterious forest clearing where several trees have fallen in a pattern resembling a crop circle. While exploring the area, they stumble upon a spaceship and meet Yudias Velgear, an alien from the Velgear Star Cluster. Yudias is interested in learning about Rush Duel, a popular card game among elementary school students, as he believes it could help him solve his home planet's ongoing war.