Azure Sky Tower is a special undead dungeon located in Istrakan and it is playable in the first game Boktai: The Sun is in your hands. The player can reach the tower after completing Bloodrust mansion, as it is located in the far south-western corner of the second area in Istrakan, accessible trough Byroad of The Beast. However, both ice and fire lenses are required to enter the maze, forcing the player to complete both Permafrost and Firetop Mountain. The dungeon is home to an optional boss called Silvery White Knight and the 6 special Gun Del Sol parts called "Golden Frames" as well as the infinite battery.
Azure Sky Tower is considered a special dungeon due to it design compared to the other undead dungeons in Boktai 1. The dungeon can be played trough multiple times without actually completing it with a result screen. It is also the only dungeon to be randomly generated, which makes the dungeon's floors room different for every playtrough,
even within the same save-file. The dungeon also gets longer every time it is played trough. It is also the only dungeon which prevents saving inside of it. The tower also cannot be exited without clearing all of the floors once the player has entered the second floor.
Azure Sky Tower is made up of different floors. To complete the tower, the player must reach the top floor. The dungeon starts with 12 floors and every time it's completed, 3 more floors are added, with the maximum amount of floors being 99. Every floor other than the bottom and top ones are randomly generated each time the dungeon is entered.
One floor consists of 4 main areas containing enemies, rooms, emblem doors and hazards, such as lava and ice. To reach the next floor, the player must find a locked blue door, such as those found in other dungeons. However, the key for this door is not found in a blue chest. It's carried by an undead enemy somewhere within the current floor. In order to proceed, the player must find this undead, kill it and collect the key from the loot sack. There is no way to see which of the undead is carrying the key, so killing all of the enemies found in the current floor might be nesessary, as descending and leaving the tower is impossible.
Once third of the way up, the player will enter the boss floor. These floors contain only one area which houses a mini-boss . These boss rooms are randomly generated, but always contain a skylight. After completing the boss, the player will be rewarded with three chests, one containing green apples, the second red apples and the last one solar nuts. There are three of these boss floors and they are situated every one-third of the way to the top. Every time a player clears a boss floor, the next floors get more difficult. Enemies get stronger, hazards become more frequent and new enemies which had not been in the previous floors (such as Steps) start spawning. After clearing the third boss floor, the player reaches the top floor, containing the golden gun solar gun frames as well as a warp magic square, which will either warp the player back to floor one, allowing exiting from the dungeon or warp them to Silvery White Knight , if the player holds the Luna emblem.
Azure Sky Tower uses emblems as a part of the dungeon. There are 7 different emblems, 3 power emblems and 4 emelental emblems. The power emblems are Sol, Dark and Luna and the elemental emblems are Earth, Ice, Fire and Wind. They are items given to the player after completing certain events and they are used to unlock the golden frames in the top floor.
- The Sol Emblem is given to the player by Lita after the Solar tree has reached full size. It is used to unlock the Dragoon frame.
- The Dark Emblem is given to the player after the first completion of the game. It is used to unlock the Stalker frame.
- The Earth Emblem is given to the player either by random when first entering the tower or by emblem resonance. It is used to unlcok the Phalanx frame.
- The Ice Emblem is given to the player either by random when first entering the tower or by emblem resonance. It is used to unlcok the Calamity frame.
- The Fire Emblem is given to the player either by random when first entering the tower or by emblem resonance. It is used to unlcok the Samurai frame.
- The Wind Emblem is given to the player either by random when first entering the tower or by emblem resonance. It is used to unlcok the Temptest frame.
- The Luna emblem is given to the player after every other emblem has been collected. It does not unlock any frame door, but is required to fight the Silvery White Knight.
Emblems are used to unlock doors within the dungeon. These emblem doors are found both randomly within the regular floors as well as the top floor. The top floor contains all the golden frames and the ones found in the regular floors contain chests, solar bamboos and solar stations. Emblems have no use outside Azure Sky Tower in any way.
The only way to legimately obtain the other three elemental emblems is to use emblem resonance. This is the action of linking two or more GameBoy Advances together either via link cables or a GameCube. Then the all the persons participating must go the main game menu, go to the "Link" section, select a save and "Emblem Resonance" and follow the instructions. Then the players copy each other emblems and they are gained within the save files once the game is restarted. Due to the need for multiple system and game packs, emblem resonance is impossible to do with emulators and is usually beyond the reach for many players.