Route: Oyu
In the hallway, you'll see Oyu standing in the corner, approach and talk to her to trigger another scenario. Their conversation is interrupted by the demons, so kill them all to finish the cutscene. After Oyu left, another demon busted from the wall revealing a treasure box:
- Equipment: Red Necklace - this necklace increases the amount of Red Souls from demons, but other types of souls will no longer appear.
Scenario 6-8: Oyu's Hesitation
Exit to the main hall.
Scenario 6-9: Tokichiro Sets a Trap for Magoichi
This time take the west door (save your game if needed).
Pick up a yellow book on the ground, then circle around to the other side and pick up another item near the elevator:
- File: Elevator Instructions
- Item: Magic Liquid
Once you picked up the items, activate the elevator, use your wind blades magic under the ceiling fan.
Take the elevator to the underground.
Consult this map from here:
Open the treasure box:
- Map: Onigashima Underground Map
Follow the path.
Hidden Red Souls #19: In the corner near the door.
Ignore the first ladder you see and enter the door. In this room, there is a trick near the ladder.
- File: Tangegashima - (Solution: Top Left, Middle Top, Bottom Right)
And 2 factory robots unless you play on Ekei's route. You don't have to fight them, though.
Route: Ekei
Walk east toward the corner, and the scenario occurs automatically.
- Equipment: Yellow Necklace - this necklace allows you to absorb yellow souls from demons directly without killing them.
Scenario 6-5: Ekei Finds a Hidden Room
Hidden Red Souls #20: In the west corner.
Use the ladder near the trick box, then circle around to the other side and enter the next door. There are 3 items here:
- File: Guildenstern's Book - a blue book on the table right next to the door.
- Key Item: Golden Key - (Solution: 1-15-14-4, 12-6-7-9, 8-10-11-5, 13-3-2-16) - examine number-puzzle safebox.
- Gift Item: Unique Mushrooms - hidden behind the steam pipe near the safebox.
Backtrack to the ladder early you ignored, climb up, use the "Golden Key" to stop the moving crates. Then jump over the crates to the other side and use "Circle Key" to unlock the door.
Route: Kotaro | Oyu | S-Rank
Scenario 6-10: Kotaro Refuses to Open up to Oyu
Pick up the small book on the ground:
- File: Tokichiro's Memo #1
Then examine the tablet in front of the statue. This puzzle is pretty easy, you just have to move the pieces from one side to another. Once finished, step on the portal to teleport to Gifu Castle.