Two thinga need to happen to unlock this and I'll spoiler up the ending so you can go blind in to the story.
1) Ryo MUST be at 51 Affinity points before the fight at the Cable car, if he isn't something bad happends
2) You must always chose the left hand option when it comes to dailogue which involves chosing a moral, wrathful or harmonious option.
Takuma's stats when I got this where as follows
Moral - 28
Wrathful - 1
Harmony - 5
Moral MUST far outweigh the other two options.
Now, the best way to achieve this is to save whenever you talk to Ryo during exploration or free roam, making sure you always get infitinty points where possible. This does mean you have to be a dick to Kunemon a few times, but this is how our trophy is earned.
During the end sequence of the bridge in the standoff between Ryo and
YOU MUST CHOSE THE MORAL OPTION to get the trophy.
*** Spoiler - click to reveal ***You'll eventually encounter Arukenimon and Cyclomon on the bridge, once Ryo is knocked off, finish Cyclomon off (I found if it takes longer than two turns, there's still a chance Kunemon won't save Ryo, so keep that in mind). Once you witness the fight between Ryo and Renamon, YOU MUST CHOSE THE MORAL OPTION, Kunemon won't act unless you do.