Nanoweb

The Nanoweb, is described in the original melody series as being designed to force a  into a more childlike mentality.

Presumably to help make a Penitatas more malleable, and subject to rehabilitation, but it also serves as a literary device, to make the characters childishness that much more complete.

Controversy
The Nanoweb does not come without controversy. It seems virtually all stories focusing on "Reforms" of the system, (such as Kayla) make its elimination a priority but at the same time others swear by it's inclusion.

The most popular theory is that the direct tampering with an individuals neural network, to force certain emotional reactions from them, is essential brainwashing, but other individuals cite that no adult could ever be reformed by such a system without some encouragement, or that the use of Nanoweb is simple a convenient plot device to get past certain narration difficulties.

Mechanics
The Shape, size, and exact workings of a nanoweb are never described. Elements such as, can be turned off (If someone's made a completes, or innocents?), is it a single implant, or a network of nanites and how exactly it effects the mind often being left to the author. Most authors come up with their own answers, but none seems to be canon as of yet. The exact nature of HOW the nanoweb works even seams to vary from story to story, with some (even Lurking Dragon's works) claiming it only enhances emotions but at other times completely over-riding adult thinking.
 * (NB) This may be a mixed result from other elements of rejuve tech, but has never been properly explained.