To allthingsjapan: You may have done this already, but you can go from A to D by selecting “Yes”. The route map should probably have point B on the short segment just after A rather than on the long bottom segment.
Two other issues:
Continuing from the above, rather than the one point on the bottom leading into episode 6, there should probably be two points. Although both are titled “The Price of Betrayal”, they lead to different routes.
I cannot step backwards from Episode 4 “With Great Reluctance”