Kamen Rider/Oni Riders

"Because I'm well trained..."

- Hibiki, summing up what makes an Oni Rider strong.

An Oni Rider is a type of Kamen Rider. They are known for their intense training and use of sound to destroy.

Origins
The concept of Oni Riders goes back to the Sengoku Era of Japanese history, where the organization Takeshi was formed to combat the Makamou, monstrous creatures that devour human flesh for food. Takeshi trained exceptional athletes to become Oni, who wielded instruments that doubled as weapons to destroy Makamou with pure sound. The group originally started as a partnership between the Oni warriors and humans, but in present day is more of a training and support group for the Oni. The organization, despite its age, still exists to this day, with offices and agents all across Japan.

Naming
When one becomes an Oni Rider, they change their name to reflect this. Oni names are always Japanese, and end in the suffix "-ki", meaning "oni" or "demon". Names tend to translate to things like Echoing Oni, Majestic Breath Demon, and Beheading Demon.

Becoming an Oni Rider
Becoming an oni is actually one of the safest ways to become a Kamen Rider (if one counts Oni as Kamen Riders), but it isn't easy. Becoming one requires routine intense training, and getting stronger also requires such training. Indeed, training is a major part of being an Oni, and neglecting it is a very bad idea if one seeks to keep their power.

Transforming
For an Oni Rider to access his Oni Form, he must take his transformation device (a tuner, for instance), activate it (in the case of the tuner, tapping it against something to have it emit sound), state their Oni name, and bring it to their head. Their respective element then engulfs them and transforms them into their Oni Form.

Powers
Oni fight using instruments that double as weapons. Such weapons include drumsticks that double as clubs, a trumpet that doubles as a gun, and a guitar that can be converted into an ax. Oni tend to have powers revolving around elements, usually fire, wind, and electricity. While techniques tend to be determined by who was the Oni's mentor, there are some common techniques that are found in many Oni, such as Kitōjutsu - Onizume, where the user forms their hands into extremely sharp claws.

During 2005, Oni Rider Hibiki accessed a power known as Kurenai Form, which he accessed through tough training. The form effectively doubles the power of the user, and turns them red.

Armed
The most powerful form any Oni Rider can access is Armed Form. The form has only been accessed by Hibiki, who, after intense training, was able to use the power of the Armed Saber power to access Armed Form. Armed Form is considered the Oni equivalent of the super mode.

The only modern Oni who has accessed this form, as far as anyone knows, is Hibiki. The Armed Saber initially took his powers away when he attempted to use it, and he had to undergo intense training to restore his powers and become worthy of the weapon.

Armed Hibiki is the result of Hibiki entering Kurenai Form and using the Armed Saber to fuse with his Disc Animals. While the only statistics available are from Hibiki, Armed Form is insanely powerful, able to punch with the force of 40 tons, and kick twice as hard. The Armed Saber itself allows Hibiki to access the powerful "Ongeki Ha: Kishin Kakusei" finisher, where the user can either create a blade of fire from the weapon that extends to up to 100 feet to slash an opponent, a crimson cyclone to hit multiple foes, or a fiery sword beam that can cut into even the toughest of armors.

While Hibiki is the only known modern Oni (or rather, only know Oni, period, for that matter) to access Armed Form, in theory, any Oni could use it, provided they have the proper training. However, the sword is within Hibiki's possession, perhaps for the best, however, due to the sword being able to take an Oni's power away if they are not prepared.

Do Onis Count as Kamen Riders?
The status of Oni Riders as Kamen Riders is debatable, due to them being very different in terms of powers. While Kamen Riders come from all walks of life in terms of their powers, Oni tend to be very unconventional in comparison to their more well-known brethren. An Oni does not transform with a belt, nor do they proclaim "Henshin!" when transforming. Most Oni finishing moves revolve around using very precise movements and techniques involving sound, with few techniques in Ongeki involving something that could be counted as a "Rider Kick".

Whether Oni count as Riders depends from person to person. It should be noted, however, that Oni Riders are officially recognized by the Kamen Riders as Kamen Riders.