You watched the series. You know what happened. Then Yuu looks at Adachi and chooses mercy instead of judgment, and everything you thought about that ending gets unmade. This is what the game showed you in a branching menu, the anime makes you watch a person decide to save someone everyone else has already condemned. The animation cuts corners, but the choice it's asking you to make doesn't.

Yuu learns about Adachi's past and the circumstances that shaped him. With that knowledge, he makes a single decision meant to save Adachi. This special gives the Persona 4 the Golden Animation series an alternate ending, told in one episode. It carries the franchise's blend of action, mystery, science fiction and the supernatural, with the tension of a thriller.