If the opponent activates the effect of this card, the effect is considered to be controlled by the controller for this card.
There is no limit to the number of times you can activate this card's effect in a single turn.
If 2 "Koa'ki Meiru" monsters you control are destroyed simultaneously during the End Phase you can only activate this card's effect once and add 1 "Koa'ki Meiru" monster to your hand.
If 2 "Koa'ki Meiru" monsters, one you control and one your opponent controls, are destroyed at the same time, both players can activate this card's effect. The effects will form a Chain. Chain Link 1 is the turn player's effect.