The first time D-Dive activates. This is made awesome by the fact that Bosch has first Knee Capped Ryu by fencing-foil, then has run it through his windpipe when this happens.
And in the final battle of Dragon Quarter, Ryu pushes his D-counter to 100% and is still unable to defeat Chetryre, but rather then give in to death, he literally goes past his own limits and engages in a truly epic Beam-O-War that concludes when Ryu reaches 167% and utterly crushes the living Weapon of Mass Destruction.
has excellent music and does a great job of setting up the story.