Owner
Owner or original owner (元々の持ち Motomoto Mochinushi) refers to the player that originally possesses a card. The card's owner is distinct from its controller, as while the controller of a card may change, its owner cannot.
Upon beginning a Duel, all cards in a player's Main Deck, Extra Deck and Side Deck are considered to be owned by that player.
Token Monsters are considered to be owned by the player who Special Summoned them. Therefore, Ojama Tokens Special Summoned by the effect of "Ojama Trio" will return to the side of the field of the player who activated "Ojama Trio" if "Owner's Seal" is activated.
Changing control
By default, cards remain under the control of their owners, but several cards can change control of cards, such as "Change of Heart", "Brain Control", "Creature Swap" and "Enemy Controller". When a monster switches control, it is placed on the new controller's side of the field.
When a card leaves the field, is returned to the Main Deck, or is detached, it is moved to the owner's hand, Main Deck, Extra Deck or Banished Zone (depending on where the card would be sent), regardless of controller.
