If my opponent has 7 or more cards in their hand, which player chooses the cards to be trashed according to this [On Play] effect?

The player who activated this [On Play] effect chooses 2 cards from their opponent's hand face-down.

[ST10-010] - Trafalgar Law (Ultra Deck: The Three Captains) - One Piece Card Game

[ST10-010] - Trafalgar Law (Ultra Deck: The Three Captains)

Card Description

[Blocker] (After your opponent declares an attack, you may rest this card to make it the new target of the attack.)[On Play] DON!! −1 (You may return the specified number of DON!! cards from your field to your DON!! deck.): If your opponent has 7 or more cards in their hand, trash 2 cards from your opponent's hand.