The Coma 2: Vicious Sisters

This achievement is for getting the good ending which requires you to get three items from doing side missions:

Moon incense This one you get automatically after you do the long hiding from Dark Song and encountering a mirror in the old library.

Blood ruby You should get this automatically if you acquired the Spectral Incense before entering room 501 in 5F Ward at Sehwa Hospital (Spectral incense is on the floor of the Butcher shop in the Dokkaebi market, best time to get this item is when you have back tracked for the T-Money card)

Holy water of restoration This one is done close to the end of the game, at the Sehwa hospital morgue (using a Wight Burrow in the room on the right on the bottom floor) you will be tasked with a maze with multiple doors, only using the correct doors will let you get through. First you want to take the 5th door from the left, the one in front of the guy reading a newspaper. Second door you want to take the 3rd door from the left, which is the door on the left of the conductor with stairs drawn on it. Third door you want the 2nd door from the right, it looks like it's bolted shut. This will lead to a secret area where you have collectibles but more importantly the holy water of restoration

Make sure you have these three items before entering the site for the blood ritual (the point of no return), Yaesol will appear with a save point before you enter the room, in fact the game won't let you enter till you talk to her and she will use the three items to create the Sanctified Moon Incense. Now just finish the game and after the un-skippable end credits that go on for half a millennium you should get the achievement

NOTE: Whatever you get as an ending on your first play through, seems to glitch the other one. I have played through and tried to get the 2nd ending twice and still not unlocked it and finished the game, so the endings may possibly glitched or it may just be me