After you defeat Phantasmurai in the Gourd Pond Museum, you and your friends decide to check out a ghost story at school at night, during the festival at the Mt. Wildwood Shrine.
Rooftop Fireworks!
There is a festival at the Mt. Wildwood shrine, and you and your friends talk about the seven School Mysteries: famous ghost stories that take place at schools, like a self-playing piano and infinite stairs. Bear says he's heard of another one lately: a voice at night that says "wanna play..." Bear suggests that you check it out right now, since you can go to the school roof afterward to watch the festival fireworks.
Before you go, you should check out the food stalls at the festival. There is a lot of good food to help you befriend Yo-kai.
When you're ready, go to the side of the school and talk to Bear. He says that you need to find the keys to the service entrance. The keys are inside of the school. Go into the door next to Bear.
Go north and talk to Eyepo if you wish. Then check the cork board in the middle of the back wall. You find the key, but suddenly you hear the creepy voice that Bear mentioned. Then you see a ghostly figure, and suddenly the others have disappeared!
The Vanished Trio
The voice challenges you to find your friends.
Go to the bottom-left of this area, where there is a Mirapo that can warp you back to the school after you talk to it.
Go northwest from there and you will notice a bunch of desk blocking the hallway. Then you'll notice one of your Inspirited friends going into the bathroom.
Go north and up the stairs. If you go to the right, you can go up the hallway to find a treasure. Then go back down and go to the right until you reach a science classroom. You hear the creepy voice again, and Whisper senses an aura. Go up to the top of the room and use the lens to find a hidden Rattelle.
Ratelle's Rib
Talk to her and she will make Bear appear. She refuses to give him back unless you find the rib that Bear took from her. Bear said that he took it to his homeroom, which you know is room 5-2. Go to the left and enter the classroom that has 5-2 on the outside wall. Check on one of the upper desks to find the rib.
Talk to Ratelle to give the rib back. She will release Bear, who goes up to the roof to wait for the fireworks. Ratelle says she's lonely, so you befriend her.
Now you can go through the northwest door of the science classroom, so do that. Go as far north as you can, then go as far west as you can. Finally, go up the stairs.
The Poor Piano
Go as far south as you can go, then go as far west as you can go. Enter the music classroom and go up to Eddie. Then use the lens on the piano to find Cupistol. Talk to him, and he asks you to stop Eddie from criticizing his piano playing. Then he asks you to find his Sheet Music in the library so that maybe he can play well enough to stop the criticism.
Go all the way east and go through classroom 3-3. Go into the library at the end of the hall and go to the upper part of the room. Check on the shelf to find the Sheet Music. Go back and give Cupistol his sheet music. Eddie is satisfied that the piano was not being played by a ghost, so he goes up to the roof.
Cupistol unlocks the western door of the music room, so go through and go west, then go down all the stairs until you're on 1F. Go east and talk to Eyepo to heal and save, then go north into the bathroom.
One Person Left!
A huge creepy spider Yo-kai, Tarantutor, drops down from the ceiling! You have to target Tarantutor's four front feet to make it fall off of the ceiling, then hit its belly while it's on the floor.
Fireworks!
After you defeat it, Whisper worries about the rise in unfamiliar Yo-kai, which means something big is happening.
Go to the left side of the hallway and go up to the third floor, then go east until you reach a hallway going north. Go up that hallway and go up the stairs at the end. Then go through the door to the east to meet your friends. You'll watch the fireworks while the mysterious Yo-kai boy watches you all.
This ends the chapter. The next chapter is The Checkup of Doom.