To get the "Lunar Tear" trophy, a Lunar Tear item, and revisit Kaine's house from the original NieR, first unlock the "Emil's Memories" side quest. To start the "Emil's Memories" side quest, successfully complete the main story mission that takes you to the forest. Defeat the Castle boss, then return to Pascal to complete it. Next, find Emil's traveling shop. It is located northwest from the City Ruins: Center, near the Desert zone entrance path. Shoot his car to stop him. Do not worry, as it will not hurt him. After talking to Emil, you will need to interact with a Lunar Tear. Lunar Tears are found throughout the open world. You can find one easily in the Shopping Mall area or the Amusement Park. Cross the long bridge by the City Ruins: Near The Tower marker to enter the Shopping Mall. From the entrance doors, pass under the escalators and look in the overgrown trees. It is on the right side - look for a bright light to find the Lunar Tear. Collect the Lunar Tear to begin the "Emil's Memories" side quest. Emil will appear right behind you and give you the quest. There are five Lunar Tears available to collect. After finding the first one and starting the quest, the rest will appear on your map as large red areas to explore. Search the indicated locations to find all five Lunar Tears:

Shopping Mall: At the entrance, look behind the escalators near the trees.
Forest Zone: It is found in the caves south of the entrance.
Park Ruins: Proceed down the central path of the ruins, then take a right and enter the area with the shop vending machine. It is found in the back-right corner.
Desert: Look for the large rocky hill in the center of the desert zone. There is a narrow cave. Drop into the hole, then navigate to the exit that leads back up and out of the underground. Once you are back up top, long jump to the platforms ahead, staying up high until you reach an alcove with a tree. It is found to the right of the withered tree.
Flooded Coast: Travel south from the Flooded Coast: Coast marker. Look on the very edge (lowest point) to find it on the mud beneath the ruined concrete.

Once you have collected all five flowers, Emil will give you the Elevator Key item that opens a special elevator in the Shopping Mall area. Use the key on the elevator located to the left of the Shopping Mall entrance. The elevator is up a small set of steps, covered with the roots from a huge tree. Take the elevator down to view a secret cutscene with Emil explaining his past and filling in some of the gaps between the original NieR and NieR: Automata. There are Lunar Tears everywhere, and Emil will give you one. The house itself is Kaine's —- her home from the cliffside village in the original NieR.