Ys Origin/Wailing Blue

At the entrance of the tower, fight the two waves of monsters. Once defeated, Shion will give you a Crystal and demonstrates its power by purifying a demon statue into a Goddess statue. It can also be used to teleport to other Goddess statues. Eolia will give you a Lila Shell that can be used to communicate with her.

Go up to the first area and defeat the glowing red monster to remove the seal on the chest. It contains a Celcetan Panacea which will raise your maximum HP. Continue right and down to the next area. There are three more glowing red monsters that are sealing a Cerulean Flabellum on a pedestal. It is one of the holy artifacts of Ys and will unlock the wind skill once acquired. Go up the stairs and down the lower area to the right. At the top right is a switch that will raise some platforms. Go back to the upper part and jump across the platforms. For the last platform, you will need to use the wind skill to jump across the larger distance. Keep going right and up the stairs. The next room has a demonic trap that will transport you to another room. Purify the demon statue and go down. Go right and up the stairs to the next area. In the middle near the stairs, climb up the platforms and go left. Step on the switch to raise a platform on the right side. Go to the platform and jump across. Open the chest to receive a Roda Fruit. Go back to the middle area and go down the stairs. In the next area, go down the left set of stairs. Defeat the glowing red monster at the bottom to reveal a circular glyph on the ground that will launch you to the upper area. Open the chest to receive an Emerald. Step on the switch to unlock a door. Go back up the stairs and go down the right path and through the unlocked door. Continue around the outside of the tower to another room with chest. Open the chest to receive a Blue Moon Crest. A Roo will enter the room and speak in a Roonic language, but cannot be understood. Give the Roda Fruit to the Roo. It will use a Cleria Ore to strengthen your weapon one level. Go back to the previous Goddess statue and place the Blue Moon Crest in the alter at the top. Drop down the hole that opens up.

(Yunica) Boss: Vaguillion
Vaguillion is a large winged demon that will be stationary and split off into a swarm of bats when it moves around. While in bat form, it is invulnerable. When it reassembles it will either use a claw attack or breath fire. Occasionally, when it moves in bat form, it will move again instead of assembling. After it loses half of its health, it will split off into two copies with the same attacks. Either one can be attacked.

There is a small window of time after it reassembles where you can safely attack. You will need to move towards it backside to avoid its claw and fire attacks to keep attacking. Afterwards, you will need to quickly move out of the way to avoid the bats. Keep repeating until it is defeated.

(Toal) Boss: Galleon
Once the boss is defeated, go up and drop down the hole. There are two chests containing a Bronze Key and a  Mask of Eyes. Drop down the platform and go back to the area before the trap room. Instead of going to the trap room, go to the locked door and use the Bronze Key to unlock it. One of the sections of the wall has a symbol on it. Equip the Mask of Eyes to reveal a hidden room. Inside the room is Rico who is injured. He will give you a Blue Necklace. Go to the trap room and equip the Blue Necklace. The trap won't automatically teleport you but it will pull you towards the center. Keep moving towards the edges and defeat the four red glowing monsters to remove the trap.

In the next area, go up to top area. Jump diagonally on the platforms and to the right is a chest that contains the first tier boots. Jump across the raised platform and go up the stairs. Go the left set of stairs and step on the switch to open a locked door. Go all the way right and to the next room. Open the chest in the caged area to receive a Beast Medallion. The caged area will seal up and three monsters will ambush you. Defeat them to remove the seal. Go back to the previous are and go up the right set of stairs and through the unlocked door. Go around the outside of the tower. In the area, defeat the glowing red monsters to unseal the demon statue and the door. Purify the statue and place the Beast Medallion on the door to unlock it.

Boss: Velagunder
Velagunder has several attack.
 * Spit out a wave of green poisonous bubbles.
 * Shoots flame that follows your movement.
 * Swipes with large arm.
 * Spits out bugs that leave a slippery trail when they move.
 * Suck the air to pull you towards it mouth to chomp and restore health.

Attack the bottom center mouth and move away when it starts to attack. Attack any bugs that it spits out because its sucking attack will heal if it eats any. After enough hits on the mouth, it will be stunned and you can jump up its arms to attack the vulnerable spot on the top. When it starts moving again, jump back down and attack the mouth again. Keep repeating the pattern.

Once Velagunder is defeated, the platforms behind it will raise and lead to another room. Go up the stairs to the Flooded Prison.