Rin differs from her main counterpart in various ways. She and her family have had no participation in the Holy Grail War ritual, having never even heard of it or the Einzbern family. She fell for Shirou in the same manner after seeing him stubbornly attempt a high jump that was impossible for him, but started displaying her feelings for him more openly. She was allowed into the Mage's Association at a much younger age, directly after graduating middle school, and put under the direct tutelage of Kischur Zelretch Schweinorg. She was given the assignment to claim the Class Cards along with Luvia, and she was given the Kaleidostick, Magical Ruby, to accomplish the task.
Similar to her Fate/Stay Night counterpart, Rin has blue eyes, and wears two black ribbons on each side of her long hair. She wears a red long-sleeved shirt paired with a black mini-skirt and thigh-high socks. She also wears her school uniform the same way as she usually does, but is more often seen with shorter sleeves than the usual long ones.
Her other casual outfits often vary; but for the most part has outfits with tinges of red; including thigh-high socks and shorts or skirts of various patterns that reveal much of her legs.
Her magical girl outfit is also similar to her Fate/hollow ataraxia counterpart; complete with a red-and-white themed dress, cloak, and animal ears.
Like her original counterpart, Rin has a resourceful, perceptive, and serious personality. She also shares the original personality on being tsundere towards Shirou (albeit being more cliche than usual). Rin has a very competitive rivalry with Luvia, especially regarding their mutual feelings for Shirou. Their fighting brings great destruction all around them, and it often brings them larger problems afterward. They do share a deep friendship, but it is overshadowed by their fighting and constant mistrust towards each other. Because of how she needs money, Rin is shown to comically willing swallow her pride in order to get a job of high wage.
It is stated many times by others (mostly Ruby and Luvia) that Rin is conscious of her chest size.
Fate/kaleid liner PRISMA☆ILLYA
Rin arrives in Fuyuki with Luvia, but their fighting causes their Kaleidostick's to reject them and cancel their contracts. Ruby ends up in the hands of Illya, and due to the Kaleidostick taking a liking to her, Rin forces her to act as her "servant" and collect the cards in her place.
Rin and Illya will later on have to team up with Luvia and her protegee, Miyu Edelfelt, collecting in the process most seven Cards of each class. After collecting the Berserker Class Card, she receives a phone call from Lord El-Melloi II. He congratulates her for collecting all the Cards and says that the Great Father has said he would not mind taking them as his pupils but however before they may study thaumaturgy, they must both learn common sense and that fortunately the country were they currently were, Japan, values cooperation and harmony, ordering them to study there for a year.
Fate/kaleid liner PRISMA☆ILLYA 2wei!
Due to her situation, she has to stay in Luvia's mansion working as a maid. After facing Dark Illya and the Enforcer, Bazett Fraga McRemitz, Rin discovers an eighth card located in the dead center of the base of the earth pulse. After finishing with their preparations, they face the manifested Heroic Spirit for the first time and it's revealed that he belongs to the Archer class.
After he managed to escape in the city with Vimana, the group meets with Caren Hortensia who reveals that she already had activated a hypnotic barrier to repel people for a square kilometer around their location. Figuring out that their enemy was going to the Mount Enzou, they rush to him and end up fighting him again.
Following the clash between Illya's Quintett Feuer and Gilgamesh's weakened Enuma Elish, Rin and the others are paralyzed by unknown ennemies, who were installing a Berserker Class Card and the Archer Class Card of Gilgamesh. They claim that they were there to take Miyu with them. The people around the area are then flashed by a white light who transports them to an alternate universe.
Fate/kaleid liner PRISMA☆ILLYA 3rei!!
Rin and Luvia are captured by the Ainsworths, brainwashed and transformed into servants of the family. They chase Illya after she is also captured and fight her alongside Angelica with Nameless Class Cards. They are eventually freed from Angelica's mind control by Gilgamesh and Bazett and end up joining again Illya's group.
During the fight, she manages to catch the alternate version of Shirou Emiya in the air after he was severely injured by Sakura's surprise attack and Beatrice's Mjölnir. She stays by his side till the end of the battle, trying to heal him but unsuccessfully. Bazett then comes to her and gives her back her pendant saying that she found it after being transported into this world. With that, she manages to fully heal him. Shirou then offers them to stay in his place if they have nowhere else to stay. Rin then reunite with the others in the living room to hear about Shirou and Miyu's past.
After learning about Shirou and Miyu's past, Rin, along with Bazett and Luvia, then discussed the matter concerning the Ainsworth goals. Because of their understanding of Magus's mindset, Rin suggests that their goal isn't simply world salvation like the Ainsworth stated.
Rin is an accomplished magus, and when allowed by Ruby to assume a Magical Girl form, displays great capability. Though normally competent, her conflicts with Luvia often cause them to perform various embarrassing blunders that leave Illya and Miyu with a negative opinion of their skills.
Like her many other counterparts, Rin primary offense spell is the Gandr curse, which manifest in typical fashion as a hazy black shot with crimson outlines. She is able to concentrate the mana for the curse in her index finger and fire a small barrage in little time, each shot capable of slightly burning the area they hit. While Rin does possess the ability to use healing magic, she admits she is a rather weak user, requiring her quite a bit of time to even stabilize a wounded Shirou before she could actually heal his injuries.
Interestingly, she is in the possession of the Azoth Sword but unlike her Fate/stay night counterpart she occasionally begins large rituals that requires jewels with the command Sign, follow by a fold of how many jewels she is using.
In her quest to humiliate Luvia, Rin has also taught herself the use of the Shared-Pain curse, a kind of witchcraft technique that slaves an individual to another's sense of pain.
Like her other counterparts, Rin is also shown to be capable in hand to hand combat.
Rin is able to use a support spell named Thor's Hammer (トール ハンマー, Tōru Hanmā?), a gun battery considered as a high speed rotation of the magic amplification circuit. She first starts by pulling off the Azoth Sword and throwing eight jewels that will align in front of the weapon. The spell consists of a large ritual with eight steps that will build the amplification circuit where she will recite the incantations in German. After activating it, she allows Illya and Miyu to shoot a powerful charged beam at their opponent.
From First to Eighth.
First, spring thunder... whirl.
Second, violent thunder... race.
Third, thunderclaps... dance.
Fourth, roaring thunder, to course.
Fifth, a hundred thunderclaps.
Sixth, heavy thunder... surround.
Seventh, Heaven's thunder... rage.
Eighth, divine thunder...
Display you providence!
Kaleido Form: Ruby
Being an experienced user of the kaleidosticks, Rin has displayed many advanced techniques while in her Ruby form. She was able to briefly stall a corrupted Saber by forming a mana-blade at the top of Ruby, which was durable enough to clash with Excalibur.
She was able to freely fly and leviate, able to divert mana for either physical enhancement or shielding at near immediate speed, and understood the use of the Include function for the Class Cards.