Ladybird

Ladybird (レディバード) is a character introduced in Souyaku Toaru Majutsu no Index.

Appearance
Ladybird has the appearance of a 13 or 14 year old girl. She has long bright red hair, and red mechanical eyes, which sometimes display images. She is barefooted and wears something like a racing swimsuit, with an orange and black coloration resembling that of her, as well as several belts around her thighs.

Brain
Although Ladybird largely fits the definition of an android, being constructed from purely mechanical parts, there is one aspect of her which does not - Ladybird incorporates pieces of brain matter extracted from human bodies. Her body's structure is modelled on that of a human and she has a similarly designed brain. (セルロースナノファイバー‎‎‎) was used to create delicate wires even thinner than cranial nerves, however unlike in a biological brain, leaving them in their active state causes them to automatically replicate. If they run out of room, they will try to forcibly fold themselves up for space. The cerebrum's frontal lobe was noted by Hasuu to be particularly troublesome. In order to counteract this, Ladybird must take a foreign object (i.e. human brain matter) into her brain so that the resulting rejection reaction will constantly provide the right amount of damage to her brain and keep it at the desired size.

Ladybird has automatic extraction organs, long and translucent, which emerge from a hatch on her back. When Ladybird needs to take in new brain matter and is close enough to a suitable target, they will wrap around her victim and drag their target into her back for extraction. This cruel design has been compared to that of an autonomous iron maiden. When Ladybird needs new brain matter, after leaking a dark liquid from her mouth and nose, she experiences an immense hunger which overrides her will.

Being modelled after the structure of a human body and with the structure of a human brain (with mechanical processing noted as conceivably being able to 'observe' waves or particles like a human brain does), Ladybird is capable of using an esper ability. This ability changes whenever new brain matter is introduced due to changes in the rejection and damage pattern, with Ladybird having been shown using a telekinetic, then a pyrokinetic, and then a wind-based power. Rather than being a brain given a body like the esper cyborg Rensa, Ladybird is described as a body given a brain.

Equipment
Ladybird wields a 60cm machete known as Left Arm (防御の剣（レフトアーム）). It is made of the artificial element Saintium (セインティウム‎‎‎), which has a metallic bond strength 56 times greater than depleted uranium. As such, the blade can easily stop a warship's armor-piercing artillery and be used to deflect bullets, though it is too heavy for a normal person to wield.

As well as a smartphone on each shoulder, Ladybird has several belts around her thighs with skinny tubes which contain rolled-up silicone keyboards and clear bottles filled with thick, clear liquid. The liquid in the bottles is a discharge machine oil (放電機械油) which reduces the frictional wear on her joints, as well as a room temperature superconductive fluid which allows her to safely release her excess energy