The Manager
Follow the guide to get Damage until you reach Victorian Stairs. Go down the stairs, take the stairs to your upper left, go up the stairs and take the stairs to your upper left again, go up the stairs and avoid the chaser, then go right and through a red door. Find a jukebox and keep interacting with it until the event is triggered, then go back through the red door and interact with the NPC.
Uninvited Guest
Follow the guide to get Damage until you reach Victorian Stairs. Go down the stairs, take the stairs to your upper left, go up the stairs and take the stairs to your upper left again, go up the stairs and avoid the chaser and cross the left bridge and go up the right stairs. Go down the left stairs, and enter the red door at the top. Interact with the mirror, and then the door.
UFO Watching
Follow the guide to get Toxic until you reach the Apartments. On the second floor, enter the fourth door to the right. Inside is an NPC looking out a window. Walk up to the window to watch a UFO flying above a distant city.
Rave Cave
Follow the guide to get Gelatinous until you reach the Stone Ruins. Once there, take the path to your right, then through the only exit at the end of the corridor. Next go down the stairs and take the first doorway you see. Take the exit at the bottom left. You'll see a flashing hole in the wall of the room you end up in, interact with it to trigger a full-screen event.
Hellflower
Follow the guide to get to get the Spiderlily menu theme. Interacting with the sitting girl will show a full-screen image, and she will disappear. You can then find her in a random location in Red River and repeat the event.
Spa Day
You'll need at least 300G for this event. Follow the guide for Vortex until you get to the Bathhouse. Take the bottom ladder, then the bottom right ladder, then the top right ladder, then the top left ladder, then the bottom right ladder, then the bottom ladder, and then the middle bottom ladder. Enter the doorway and interact with the clerk, and then the swimsuit hanging on the wall.
Carousel Ride
You will need the Glassy alter for the shortest route to this event.
Follow the guide for Apparition until you reach the carousel in Misty Forest. Climb up the steps onto the carousel to ride it.
Reactivation
You will need the Verdant and Metallic alters for this event. This event is necessary to unlock Ending #3.
Follow the guide for Verdant. When you reach the location of the alter, go back through the doorway, down the ladder, and enter the doorway to the right. Go down the hall and into the room with the giant robot. Equip the Verdant alter and hold the space key. Then equip the Metallic alter and interact with the robot.
Tetsuko
You will need the Glassy alter for this event. This event is necessary to unlock Ending #2.
Follow the guide for Celestial, but instead of taking the left ladder in Dark Town after the boat ride, take the right ladder and go through the doorway. Once you're at the Docks, use these teleporters: Left, bottom left, upper right, middle, bottom, middle, and bottom right. Go through the open door to get to Empty City (you'll need the Glassy alter in this area), then down the ladder and through the doorway. Go through the bottommost doorway, through the hall and the next doorway, then take the uppermost doorway to the left. Take the only other doorway, then go through the flashing door to get to the Subnexus. Go through the top door and interact with the girl in the room. This event can only be done once.
Tetsuko's Past
This event is necessary to unlock Ending #2.
Follow the guide for Damage until you get to the Hospital. Take the rightmost elevator, then the second door to the left, then the second door to the left again.
Amputation
Follow the guide for Damage until you reach the Hospital. Take the elevator on the right and keep interacting with the door with the bloodstain until you can enter. Go all the way up the hall to trigger the event.