Set before the end of the second Yu-Gi-Oh! anime series (Yu-Gi-Oh: Duel Monsters), between the Grand Championship and Millennium World, Capsule Monsters involves Yugi, Joey (Jonouchi), Téa (Anzu), Tristan (Honda), and Yugi's grandfather Solomon (Sugoroku) being pulled into a world where Duel Monsters are real. They find monster capsules that they can use to summon monsters. However, in this strange new world, they battle monsters and when their own monsters are attacked, they feel the pain.