Child of Light

Also known as Kanade, she is the guardian of the Plasma Bell, and the strongest among all of the Tower Guardians. She is also the third known produced model among the maintenance droids, her successors being the androids located in the Second Tower of Ar tonelico: Raki and Reki.

As her stats, attacks and description demonstrate, she is quite an strong opponent, with her skills being the following: Flowing Form - First Dance and Flying Form - Rising Ring Falling Sun, both of which deal large physical damage to a single target; Destroy Form - Absolute Strength Impact, which causes turn delay in addition to dealing large physical damage; Dance Form - Ultimate Dance of Warrior Princess, which can instantly kill its target in addition to causing large physical damage; and finally, a Lv. 3 Stored Attack called Ruin Form - One Hit Kill, which causes extremely large physical damage. In addition, she is quite speedy, so that means you will have to resort to other tactics beyond just attacking with your Vanguards and depending on Song Magic if you expect to defeat her, especially if you intend to fight her several times. As a side note, while almost all the battles against her are called sparrings, you'll get a Game Over if your party is defeated, so be careful.

First, you will have to stock up on healing and debuff items in order to deal with her large damage output, and make sure to have all your characters equipped with the best Defense-raising Grathnodes prior to entering in battle. After this, attack as hard and fast as you can while keeping your Reyvateil either charging a Red Magic to attack, or a Blue Magic to support your party, while always paying attention to whenever Kanade tries to use Ruin Form - One Hit Kill, which could end up ruining your plans. Likewise, take care with her Dance Form - Ultimate Dance of Warrior Princess and Destroy Form - Absolute Strength Impact attacks, since their additional effects can both ruin your strategies and decimate your party.

Finally, remember that you have to defeat her a minimum of five times in order to get the Child of Light Song Magic for Shurelia, and the stats table shown in this article only shows the stats for the first battle against her. Whenever you defeat her, you will have to fight five battles to challenge her again, and in the next battle, her stats will increase in the following way: Kanade's stats will max out at the 203th battle, at which point she will become the strongest and toughest enemy in all the game, but long before that, she will be already hitting for maximum damage and having a very-hard to penetrate defense and total immunity to all elements.
 * HP: Increases by a 5% (4500). Max 999999 HP.
 * Attack: Increases by a 20% (around 511). Max 9999.
 * Defense: Increases by a 20% (286). Max 9999.
 * Speed: Increases by a 20% (50). Max 9999
 * All Resistances: Increase by 10. Max 100 for each.

Finally, as mentioned above, defeating her five times allows Shurelia to summon her with the Child of Light Song Magic, which charges faster and requires less MP than Ar tonelico, but can still deal similar, and even superior, amounts of damage.