[OP11-084] - Kuzan (A Fist of Divine Speed)

If I select a Character I played this turn as the target of this [When Attacking] effect, will that Character be able to attack active Characters?

No, it will not. This effect allows the selected Leader or Character to attack active Characters. However, because you cannot declare an attack with a Character on the turn it is played, the Character in question will not be able to attack active Characters.