Shindo Max Trust - Earn Maximum Trust with Shindo
Must be earned by the end of chapter 5.
If you haven't got it through natural game play by chapter five then during the time you are in the garbage area facing the "zombie" hollow children prototypes there is two times where Shindo is trying to open a door and leaves you to fend of enemies. These enemies keep respawning long after the door is open so just stay put and keep taking them out getting head shots, one shot kills and multi kills using your assault rifles sonic wave.
I even managed to get the cop to max trust in this section and you only have him for a few minutes, though there's no achievement for that :/