Ever since an extraterrestrial stole something precious from him, 5th grader Yuhi Ohdo knows that aliens are real - even if nobody else believes him! That's why he and his twin sister Yuamu created their very own alien investigation agency known as Ultraterrestrial Tracker Squad (UTS). When Yuhi's not busy tracking down aliens, he loves to Rush Duel. Always full of energy, Yuhi and his Jointech monsters will duel anyone - even if they're from a planet a billion light years away!