Rika's eyes are coppery orange and ringed with a burnt-looking brown. Due to a birth defect that left her without pupils, the are always covered in dark-tinted goggles. Her hair is pale green, and she keeps it in a pair of messy, jaw-length pigtails. Rika's outfit consists of a long khaki coat that somewhat resembles a lab coat; a loose white tank top held together by a large zipper down the front; black shorts, black knee guards, and fishnet stockings. For shoes, she wears scuffed, chunky knee-high boots made of dark red leather. The most noticable aspect of her attire is a massive pair of canvas gloves that nearly triple the size of her hands. Each glove is decorated with a red glass orb on the back of the hand (which serves as a holding cell for a forge spirit) and a yellow line pattern. Rika is tall (7' 3) and busty, as well as being strong enough to withstand being hit by a car.
Rika has a number of gear tattoos on various locations of her body.
- One her right cheek
- One on the back of each hand
- One encircling her left eye
- One encircling her navel, which is again encircled by a larger tattoo
- A row of miniscule tattoos down her spine
These tattoos begin to rotate when Rika's Kekkai Genkai is activated. The more she exerts herself, the faster they turn. If she begins to use dangerous amounts of energy, the tattoos will begin to spread across her body. When they cover her body completely, it means she is near death. In this way, Rika's tattoos act like a warning system.
Rika's personality is very happy-go-lucky and cheerful. She is also rather gluttonous, capable of consuming huge amounts of food; however, she makes up for this by being highly diligent in her physical training, which takes up nearly all time not spent eating, sleeping, or attempting to study. While Rika is not very book-smart, she is a good strategist and excels at making split-second decisions and calculated gambles. Rika has great physical stamina from all her training, which never really ends. She almost always wears a harness weighted with lead under her shirt to strengthen her lungs and chest, and the harness is only removed when she is bathing - she even sleeps in it. Rika also wears large weights on her wrists.
Another aspect of Rika's personality is her intense phobia of large bodies of water (rivers, lakes, the ocean, etc.). This is due to the fact that she cannot swim, as she sinks immediately whenever she tries. Rika is not even comfortable with taking a bath, always preferring a shower.
Kekkai Genkai - Giyagan
Characterized by a black rotating gear where Rika's pupil would be, the Giyagan allows Rika to "download" weapons. This means that she scans the weapon and commits its structure to mental and muscle memory, allowing her to use the weapon in a fight by transforming a body part into it. She also has complete knowledge of the weapon stored in her mind, causing her to become an expert on the weapon immediately. Giyagan works on anything from knives to rocket launchers - however, the more complex the weapon, the more exhausted Rika will be after "downloading" it. Additionally, a more complex weapon will take more chakra to form the body part into the weapon and sustain the weapon. For example, Rika can use and sustain knives at a very low cost to her chakra; however, a rocket launcher would take a great deal of energy to transform into, and Rika would only be able to sustain the form for one or two shots if she wished to conserve her energy. If Rika were to attempt to "download," something as complex as a tank, the effort from doing so would leave her bedridden. Another downside to the Giyagan is that when a projectile weapon has a powerful enough recoil, the force can sometimes dislocate Rika's shoulders.
Rika's most powerful (and draining) attack is known as the Celestial Cannon. With the help of the forge spirits housed in her gloves, she turns both arms into a white cannon with eight to zero small, finlike appendages protruding from the sides, which represent Rika's fingers. The power levels of the cannon are indicated by them; the fewer fingers that are up, the more powerful the cannon becomes. The power levels range from two fingers (with eight fingers remaining up on the cannon) to ten fingers (in which no fingers are left). A higher power level requires more time to rest between shots, with two fingers being fired once a week and ten fingers, once every seven months. Another factor that affects the cannon's power is the phase of the moon. At the new moon, the cannon is weakest; at the full moon, the cannon is at its most powerful.
Due to her method of training, Rika has incredible stamina, being able to run for three days straight and strong enough to withstand being hit by a car, if given time to prepare. This stamina is the result of her weight training and running while infused with Kevlar and metal plates (which also helps strengthen her chakra). In addition, Rika's gloves are extremely heavy, as they are a Kevlar-steel alloy. With this stamina, however, Rika sacrifices a good deal of agility and stealth due to her bulk. In battle, she has few options besides a direct attack.
Rika was the result of a failed attempt by Orochimaru to create a perfect killing machine. Besides the fact that she was far too human to be successful, she was born without pupils, which left her susceptible to flash blinding, migraines, and damage to the optical nerves. She was given a violent blow to the head and left out to die, but fortunately was found by a passerby, who brought her to a children's shelter. Rika was soon adopted by a homosexual couple. She got her first name from an actress the couple liked, and her surname from the dog tag embedded in her earlobe which read "Karakuri 36, 8/14/92." This dog tag is the only link Rika has to her past; she has no memory of the incidents which led to her adoption.