Two scenarios happen here:

You fought this boss before, and this time we'll still use the same strategy as before. Pull out your ice spear and perform the secret move until the battle ends. You cannot win this battle anyway.

Consult this map for this part:

• Key Item: Red Soul Bracelet - obtained automatically.

Once you gained control of Oyu, walk around the Dragon Shrine to save your game at the Magic Mirror in the left corner. Then, go south down the ramp and use the stairs to go to the next area. Kill the 2 giant demons and open a treasure box in the corner. Then come back to the Earth Dragon Shrine and use this "Key Plate" to unlock the fence in front of the shrine.

• Key Item: Key Plate

Both doors, west and east, also unlocked. Next, enter the east door (your right) first. Continue on this hallway to the next room that has an acid pond. This room has 3 items:

• Map: Onigashima 1F Map - inside the treasure box.
• File: The Oni's Super Weapon - on the shelf to your left
• Item: Medicine - behind the giant statue

Enter the east door to another hallway, then enter the next room with the glass floor. Walk around and press L1 to block the spit attacks from the fish for a while until the red barrier disappears. Then use the ladder to go down.

Kill all the demons in this room, especially the one mounted on the wall to open a new path. Don't forget to pick up an item in the treasure box:

• Equipment: Adarga - this is Oyu's shield, go to "Inventory -> Equip" to equip this new shield immediately.

Examine the light to enter a new area. Follow the bone bridge until you reach a Magic Mirror and pick up another item:

• Equipment: Gladius - Oyu's best weapon, so equip it immediately.

Save your game and continue south.

In this room, you'll have to fight 2 giant demons. Strategy: stay away from the giant demons and charge your sword 3 times by holding "R2", once full, get close and attack, then repeat. Your charge attacks can knock back big demons, so it's very handy.

• Key Item: Sacred Flute - obtained after killing the red giant demon.

Return to the beach and give this flute to Jubei.

You are now back to Jubei.

Enter the door and use your wind blades magic to kill archer demons above the Dragon Shrine. Then examine the shrine to obtain a new weapon, earth hammer:

• Equipment: Dokoutsui

Don't forget to enhance your weapons/armor and save the game. Take the east door again until you reach the acid-pond room.

Continue down the hallway (Magoichi may show up if you play his route, so make sure you slay all the demons until they left). When you reach the orange seal, use the hammer to destroy it. Inside this room, Oyu will always come to help you if you gave her all the equipment you bought from the item shop. Now kill all the demons in this area.

• Item: Herb - talk to Oyu
• Key Item: Circle Key - on the floor

Now use the ladder in the corner to go up. It's a shortcut to the acid room then exit using the west door (your left).