In Chp.2 When you go searching for Angeals house in the area around his house are 3 glowing objects you need to interact with,(1 by the first house on your right you cant miss it. The other 2 are side by side on the right and left by some wooden structures.) Zack will say a phrase and will not pick up the object.
Go into Angeals house triggering a cutscene. Tseng calls you to the factory. As you go up to where Tseng is there are 2 more objects there.
Go into the factory. After everything in the factory is done and You get control of zack on normal you have 40 seconds to get all 5 objects. So hold down the run button.
You will be stopped by a mini game where you can get Slicin Soldier Achievement. ill make a guide there.
Then the timer will start get the 2 on the cliff you got last Zack will say i cant check what it is right now. When you get to the last 3 grab the one by the house then the next closest then the last. Then the achievement will unlock if you get them all before the timer hits Zero.
IMPORTANT INFO!!- If you do not interact with the items before entering Angeals house(first time) they will disappear, or after you make it to Angeals house(second time) During the Shell Strike they will also disappear. With the last 3 you pick up start on the right side. As reaching Angeals house can initially cause a Cutscene and for you to miss the 2 furthest from Angeals house.