The Oni is the tentative name of aliens race from Chi-one Sagittarii, that appears in Kuromukuro.
Physiology
This species is humanoid and appears to have two genders. They are red skinned beings with horns with an uncanny resemblance to Japanese oni. This species possesses a centuries long lifespans, living up to 450 years.
History
Over 450 years ago the Efy Dolgh launched an unprovoked attacked on the world of Chi-one Sagittarii, homeworld of the Oni. The Oni were subjugated but a small resistance team, managed to hijack a mothership. Using the stolen vessel, the Oni resistance followed a scout ship that was sent to Earth.
The Oni crashed their ship into the scout ship, damaging it. Both forces landed in Japan during the Sengoku era. Majority of the Oni were killed saved two. One of the survivors, Zelleager "Zell" Myundef Vishrai attempted to make allies of the humans of feudal Japan. However due to his appearance he was mistaken as a demon by the reigning Washiba Clan and hunted.
When the Washiba Clan was destroyed by the Efy Dolgh forces, he allied himself with the lone survivor Princess Yukihime and her comatose retainer Kennosuke Tokisada Ouma. Using a stolen Geoframe, the two groups managed to destroy the remaining Efy Dolgh forces before they could contact the mainforce. However the result ended with the death of Zell's comrade and the princess leaving him alone.
450 years later, and in the present day, its Gezon-Reco Squad arrived to follow up on the scout force's progress. Zell resurfaced after Kennosuke Tokisada Ouma was awaken and began aiding the United Nations Kurobe Research Institute. After the initial invasion force was defeated and apprehended, Zell learned from the clone commander, that the resistance of Chi-one Sagittarii still existed and that there was an outbreak of rebellions throughout the Efy Dolg empire.
Five years after the invasion, Earth developed spacecraft to join the fight against the Efy Dolg with the intent to liberating Chi-one Sagittarii.