Mikoto is a Genome. Genomes are a race of souless beings, created by an android named: Garland. They came to Earth from their own planet: Terra, after its destruction & reside deep underground.
Garland began creating Genomes roughly 3000 years ago to act as vessels for the Terran souls so that Terra's civilization could one day be revived by attempting to fuse it with Earth.
The fusion between Terra & Earth was a failure. The Terrans gave up their physical bodies & laid themselves to rest, placing the burden of salvation on Garland. Garland created the artificial race of Genomes, to inherit the souls of Terra once the fusion was complete.
Genomes are all physically identical to humans, but have monkey-like tails. Most of them are passive & meek, not placing much value in their own existence & viewing themselves as disposable as part of Garland's schemes. They live in the Genome village of Bran-Bal.
Mikoto was created by Garland 9-months-ago, but was created to physically resemble a 15-year-old girl with a pale complexion, blonde hair & bright green eyes. She was created to be a guide around Bran-Bal to any outsiders.
She wears pink hair clips, & wears a pink & white cropped top over a black long-sleeved leotard, a pink-& -white patterned skirt, & knee-high boots of the same color.
Quiet & formal, Mikoto, as the only Genome in Bran-Bal created with a soul, is intelligent & understands what her fellow Genomes cannot. She appears cold but is merely truthful, & while able to express her emotions, it can be assumed that she is used to not doing this as she lives alongside other, emotionless Genomes, & thus struggles showing how she feels.