If Yasuo Remorseful attacks a battlefield and is killed by Hidden Blade in response to the attack trigger, does the damage still happen?

Ruling: The damage does not happen. When the ability resolves, Yasuo is no longer present at the battlefield (he's in the trash), so the "unit here" condition fails and no damage is inflicted.

Nuances:

• The key is the "unit here" text on Yasuo's card - the ability requires Yasuo to still be present at the location when it resolves
• Even though the ability is on the stack, it checks for Yasuo's presence upon resolution