Krampus

Krampus is a "child", or soul, that you can summon to fight your way through the world of Destiny Child.

Profile
Her adorable facade may call to mind a Christmas fairy, but in reality, she is the Christmas sprite Krampus. A waking Yuletide nightmare, she hunts for human souls with Satan Santa Claus.

Krampus is an ill-tempered prankster who is always hiding her true self with a deceitful smile. Ever since Satan Santa Claus's Child disappeared, she has taken pleasure in tormenting him endlessly. Despite her youthful appearance, she is over seven hundred years old.

Children
It should be noted that in this case, the use of "child" does not mean the character is a child. Like all the other summons in this game, "child" simply refers to the soul that is being summoned.