Overview--bottom line up front: This achievement is unlocked by defeating Emil in the first of two optional fights with him. It can also be unlocked by purchasing it from the special achievement shop that becomes available after your third playthrough. If purchased, it costs 200,000 G (in-game currency). Some people have experienced a
glitch so make an insurance save before fighting Emil. See the last paragraph in case of a glitch.
Associated achievements: There are two achievements that are dependent upon this encounter with Emil. Note that both of them can be purchased at the special achievement shop that becomes available after your third playthrough. The rewards of the battle include a weapon. Since there are two achievements that require obtaining all weapons, you must defeat Emil here to as part of the conditions to unlock the two achievements.
Emil Heads is earned upon defeating Emil in the process of unlocking this achievement. It is one of the weapons that must be fully upgraded to unlock the following:
Additionally, you must have all weapons obtained and fully upgraded--including the Emil Heads obtained while earning this achievement--in order to view the Y ending which is one of the endings that must be seen to unlock:
Accordingly, if you choose not to engage in the fight with Emil, you will not obtain one of the weapons required for both the Inorganic Blade and Transcendent Being achievements and will have to purchase those two achievements as well as Naughty Children. Inorganic Blade costs 100,000G and Transcendent Being costs 200,000G.
Detailed Discussion: There are quite a few steps that must be taken in order to make the fight with Emil available:
--During Chapter 6, you encounter Emil for the first time in the Commercial Facility as you make your way to the Forest Kingdom. When you finish the Forest Kingdom main story mission, Emil will operate a roving shop. It moves quickly and you have to shoot at it to stop it. Do so and interact with him.
--Go back to the Commercial Facility and search around the area where you first saw Emil. You will find a glowing white flower. This is a Lunar Tear. Emil will show up. He says the flower brings back memories and to notify him if you find more. This initiates the Emil's Memories side quest. There are four more Lunar Tears to find.
--Markers in the form of red circles now appear on your map identifying the locations of the four Lunar Tears. You can find them in the Flooded City, the Amusement Park, the Desert, and the Forest. Three of the four are in plain view but the one in the desert requires first going into the subterranean caverns and then executing a slightly tricky jump. Each time you find a Lunar Tear, Emil is notified automatically and shows up almost immediately. When you find the fifth Lunar Tear, Emil gives you the key to an elevator in the commercial facility. Going down this elevator concludes the Emil's Memories side quest. He does not directly state it but gives a hint that the key also operates an elevator leading to the subterranean caverns where he lives.
--You can do Emil's Memories in your first playthrough but you cannot fight Emil until your second because you have to be playing as 9S to do so.
--The earliest you can unlock the first optional Emil fight is doing your second playthrough. You can also do it during your third playthrough but only when playing as 9S and not as A2. You can also use chapter select following your third playthrough to return to a point where you can initiate the fight.
--Note: Emil is at level 99. He is very resistant to damage. So, if you are at a relatively low level consider some leveling up before engaging him.--As a frame of reference, go upstream from the river that goes by the tower in the City Ruins. It ends up as a waterfall into the cavern. Turn left and go a short ways until you see a very large sewer pipe. Jump into it. Just inside the entrance is an elevator. It will open for you providing you got the key from Emil during the Emil's Memories side quest. Follow the route to its lowest point either going down a deep cavernous hole or taking another elevator. At the end are two doors. Going through them both leads you to an area with a hut. This is Emil's house.
--Attempt to pick up the glowing item under a rack of masks. The game will caution you but choose to pick up the item anyway. Return to the surface. Open your in-game map and locate Emil's roving shop. Follow it and shoot it to make it stop. Interact with Emil. He will notify you of the theft and says he has now locked his stuff up in a sealed container.
--Make a save. Return to Emil's hut. Use 9S to hack the sealed container you find there. When you exit through the door, you will encounter Emil. He is level 99. Defeating him will unlock the achievement and reward you with Emil's Heads, a weapon in the Combat Bracers category.
In case of a glitch: If the achievement does not unlock right after you defeat Emil, you most likely have experienced a glitch. In the event of a glitch, clear the cache. To do so, turn off the console by holding the
button on the console for at least ten seconds and then unplug the console for at least 20 seconds. Load the save you made just before going to Emil's house the second time. Clearing the cache will most likely remedy the problem. Return to Emil's house, hack the chest. leave through the door, and defeat Emil. The achievement should now unlock.