I just got done messing with the C path and figured out that you have to just be passive and let things slide with Shoichi's dad, but then be firm and keep pushing.
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I'm guessing that's another way of getting the bad route, because I chose to confront his dad, apologize, then keep pushing.
My guess is that if you choose to stop pushing him no matter the other choices, you're bound to get the neutral route. Pushing him in the 3rd choice is bound to get you either the bad route or the good route. Well, you know what they say, go big or go home (which, coincidentally, is the only way to get route A.)