*Highly Missable*
The mission you need to be aware of is 'Search and Destory'
Close to the end of the mission and after the meeting. Arasaka invade Takemuras' hideout. Johnny informs you that there's no point in helping Takemura as he's likely dead, the objective also sends you straight out of the apartment building.
Ignore these warnings, once you've got control back, enter the room opposite where you start and look for a hole in the wall on your left, At the back of the apartment is some steps. Go up these, OR if you have jump augmentation you can jump up the hole you fell down in. Kill the Arasaka agents to save Takemura. Makes sure you now leave with him in tow.
You can now complete the game as normal up until you hit the mission Nocturne Op55N1. Carry on through this until you reach the roof and have to make a decision. Choose "Think trusting Arasaka’s risky but worth it"
Next choose "Take some Omega Blockers" and then "Call Hanako and accept offer" This will now force you on a linear path that will guarantee you'll unlock it.
The achievement will unlock when you take the lift/elevator after finding Yorinobu. (Which means you don't even have to complete the game or get an ending).