Nanomachines are a special type of technology that's used to repair injuries, cure illnesses, create objects, and even change appearances. Sometimes nanomachines can take the form of living organisms, and they will often have the ability to live independently and have the ability to heal/repair/disguise etc. (i.e: Vanilla's Nanomachine pet and Nano-Nano Pudding). While the origin of Nanotechnology is unknown, it's likely been a widespread technique across numerous galaxies for centuries even before the Chrono Quake occurred.
Galaxy Angel[]
Vanilla with her nanomachine pet
In the original trilogy the use of nanomachine technology was done through Vanilla H, who had been using nanotechnology since a very young age. She's often accompanied by a small, luminous, and fox-like animal that she calls a "Nanomachine pet" (which follows her just about everywhere in the manga), and spent the majority of her free time in the Elle Ciel's infirmary helping patients
The ability to wield nanotechnology requires a great amount of focus. In Vanilla's case, she was able to attain complete emotional resistance and had become a very skilled user at only 13 years old at the cost of appearing aloof and inexpressive. But despite this feat, she does experience moments of distress that cause the nanomachines to go haywire, such as her route in Eternal Lovers when her jealousy of losing Tact to another girl causes her Nanomachine Pet to grow into a big wolf and attack him when he tries to approach her. This shows that the bond between a wielder of nanotechnology and the nanomachines themselves go much deeper than simply one ruling over the other.
Nanomachine Pet from the VN
The Harvester is the healer of the EDEN Emblem Frames and uses a different type of nanomachine technology that repairs ships. While she typically can only repair the Emblem Frames, Vanilla has assisted in repairing damage on the outer hull of the Elle Ciel with the Harvester before and used her Repair Wave in order to completely restore it's function during the final battle against the Black Moon. Like ammunition, nanomachines seem to be a finite resource and need to be replenished, but where the nanomachine resupply comes from is completely unknown.
Anime-wise, Vanilla has the ability to heal others but this ability appears rarely and hasn't been confirmed to be nanomachines (verbally at least).
Galaxy Angel II[]
Nano-Nano restoring her nanomachine supply
With the discovery of Pico, and its moon Femto, Vanilla was able to reintroduce nanomachines to the NEUE galaxy during the initial tour the Moon Angels took before the events of GAII. The discovery of Femto and its numerous facilities would lead to the creation of Nano-Nano Pudding, who was a single nanomachine organism until Vanilla made contact with her and fused their DNA.
By the time the Rune Angel Troupe is formed, Nano-Nano becomes the group's medic who's on call to perform any immediate healing. Throughout her route, she has a habit of over exhausting the amount of nanomachines she can use (which usually results in her own self destruction) but she had managed to commit great feats such as reviving Kazuya after he receives a fatal wound during a battle and even restores his completely severed arm. And unlike Vanilla, Nano doesn't need to repress her emotions in order to use her nanomachines. She also has the ability to completely change her physical appearance, despite not liking to do so in the earlier games.
Later on in Eigou Kaiki no Toki, during Noa's visit it was revealed that The Will had infiltrated Femto's labs and ransacked all of the nanomachine organisms they could program to repair machinery. They had left one organism behind, Cookie, whose main quirk was having the ability to obtain the DNA pattern of whatever she touched. Depending on the route, Cookie would either obtain the DNA of Lily, Tequila, or Nano-Nano and get into various different situations.
- Santa-Rosa's DNA gets mixed with Lily's when it contacts Cookie and forces Lily's conscience into a fairy version of herself (or whatever happened there.),
- Tequila mixes her DNA into Cookie and is granted a separate body from Kahlua
- In Nano-Nano's route, Cookie gains both Nano's and Kazuya's DNA and becomes their biological child in basically the same way Nano became Vanilla's child. Despite her main ability being the ability to obtain DNA, Cookie can also repair spaceships.
The First Aider is the third NEUE Emblem Frame discovered on Pico, and given its relation to the planet, it's equipped with nanotechnology that can repair Emblem Frame's just like her mother's Emblem Frame. The key difference between the two is that the First Aider can turn its nanomachines into an offensive Hyper Weapon.