The quest titled Mysterious Prelude begins an event quest chain in Infinity Nikki. The quest chain is called ‘Song of the Lost’. You’ll begin by going to the Stylist’s Guild to chat with Dada.
Once you chat with Dada, the quest under the ‘Song of the Lost’ quest chain will be ‘In the Depths of Night’.
Visit the Queen’s Palace Ruins
You’ll want to visit Queen Philomia’s Palace Ruins during the day. Specifically, you’ll want to go between 04:00-22:00 hours in-game time.
You can check the in-game time by opening the main menu. It should appear directly above the Store icon. Follow the map marker to find Locke and chat with him about the ruins.
Investigate the Ruins at Night
Once you chat with Locke, you’ll want to meet up with him again later at night. Any time between the in-game hours of 22:00-03:00 will work.
You’ll enter the ruins and use your camera on the violin statue. Pan the camera upward slowly until you see an additional box outline titled as “???”. Snap a picture to see what is revealed.
Follow the new friend. You may notice that while you are following, you end up back at the bottom of the circular walkway. You’re not imagining it, it’s working as designed.
You’ll need to “investigate” all the lamplight flowers along the path in order to continue on the correct path, otherwise you’ll keep returning to the bottom of the circular path.
Continue following the ghostly friend to the Silent Sword. You’ll obtain a token from the Silent Sword, along with a photograph that you can access from the quest section in your backpack.
Find The “Shadowed Grin”
The “Shadowed Grin” can only be found during night from 22:00-03:00. Once you reach the proper spot inside the ruins courtyard area, you’ll have the option to wait for the appropriate time. Selecting wait will fast-forward time.
Once you collect all the Black Blings in the area with the cat, you’ll need to enter the ruins by climbing up to the second level. There’s a photograph on the wall at the end of one of the halls.
Use your camera to snap a picture of it, and then follow the spectral tether back outside. When you jump back down to the ground, head to the left along the stone path. You should see some Black Blings.
Follow the path of Black Blings until you’ve collected all 99. Return to “Strange” in the courtyard. Chat with Strange to hand over the Black Blings and photograph.
Find The “White Hands” at the Tower
The tower is the tallest part of the ruins in the courtyard. Follow the quest marker to climb the tower. You’ll need it to be during the night again, from 22:00-03:00 hours.
If you’d rather not wait, you can always open the menu and go to the ‘Run, Pear-Pal’ option to change the time to your preferred in-game hours. Be warned you’ll have to play a mini-game reminiscent of Flappy Bird before the time will change, or put a checkmark in the “skip” option.
Climb the tower using the trampolines held by birds, and the springy leaf. If you’ve already visited the tower you can use the waypoint to cover some of the distance a bit faster. Obtain the token from Ms. Glove.
Go to the Inner Court Entrance of the Queen’s Palace Ruins
Make sure it is night again, between 22:00-03:00 hours. Head to the Inner Court entrance across the courtyard.
If you arrive during the day, you can interact with the marker to wait for night and begin the next part of the quest. After a cutscene you’ll want to wait again for Livie to wake up.
Chat with Livie to continue the quest. Place the tokens in the Inner Court door. Follow Livie into the Palace Ruins.
Investigate the Inner Court of the Queen’s Palace Ruins
Once you enter the Inner Court to follow Livie, there’s not much to see. Drop down into the foggy abyss in the broken stairwell.
Purify any esselings to continue. You’ll enter a dungeon area. The hallway to the right will have some blings and esselings.
Once you’ve taken care of the esselings, you can scout the area. Behind a large broken wall segment are some Dews of Inspiration.
There’s also a hole in the floor of the hallway. If you drop down, you’ll find a whimstar. You can climb back up and head back to the main hallway to progress further.
Continue along the path and chat with Locke. In the inner courtyard, you can climb the smaller tower-like building to cleanse more esselings, find Dews of Inspiration, and enter the building from the broken roof.
When you drop down into the building, there’ll be some blings, a lore book, and a stack of crates. Brake the crates to obtain a whimstar. Use the furniture to climb back up to the rooftop area.
Once you’ve purified all the esselings, the guards will open the double-doors. Drop down to the platforms in the water. If you follow the platforms to the right you’ll acquire some blings and Dews of Inspiration.
To the left, there’s a guard and an esseling to purify. Head to the main doorway and purify the remaining esseling so the guard can open the doors.
Use the floating display cases to climb back up after falling through to a lower level. Take care while climbing on the cases. If you stand too long on the glass it can break.
Once you reach the higher level, you’ll need to go through to the next room called the Doll Gallery, and walk across the pillar on the right to get to the guard in the previous room.
Return to the main portion of the Doll Gallery room after you purify the esselings and the guard. Next you’ll need to hop across more floating display cases to free the next guard from the esseling.
To the left is a parkour pillar puzzle to get to the last whimstar. Stand on the display case once you reach it until the glass breaks to get to the whimstar, or use your jump and plunge ability combo. You’ll need to move quickly to reach the whimstar case, because the small square flower-design pillars will crumble beneath you.
If you accidentally activate the transport stone tile, you’ll need to time your exit from the whimstar display case carefully to reach it, as it will continue to move once it has been activated. The transport tile will take you up to the higher level of floating display cases.
Finish your parkour journey over the display cases to the closed double-doors. Purify the esseling on the right, and on the left you can use the floating display cases to reach the last guard. Purify the remaining esseling to open the doors.
You’ll need to approach the doors as these ones won’t automatically open. Next you’ll need to leave the Palace. Use shadows on the ground to avoid falling objects.
If you get hit, you’ll start back from the point where you attempt to leave at the bottom of the staircase. It will only take one hit to knock you out. You’ll also need to watch for sudden holes in the floor, as well as falling and breaking furniture.
Return to the Stylist’s Guild
Enter the Stylist’s Guild to tell Dada and Captain Hiya what transpired. This completes the quest. Once this is completed you’ll unlock the event section ‘Tales of Mystery’.