Her nickname is 'Rin', because 'suzu' translates to 'small bell' in Japanese, and 'rin' resembles the sound a small bell makes. 'Isuzu' is also a rare name. When written as two Kanji characters, it means 'Dependable Bell', which many consider to represent Isuzu's personality and appearance quite well.
In volume 14, it was revealed that all of the Jyuunishi's names but Yuki's were derived from poetic names for the months of the year. Hers comes from "Isuzukure tsuki" / "Month of cool closings", the name for June.
Rin's childhood up to an unspecified point was affectionate, loving and normal; when she was a small child, perhaps eight or nine going by the art, she posed the innocent question to her parents -- "are you really always this happy? Doesn't anything bad ever happen?" -- and this catalyzed a long term and severe physically and emotionally abusive relationship that continued for years until she collapsed in the street and was hospitalized.
While she was in the hospital, her mother visited once and briefly in order to tell her she was no longer welcome in their home. A child of perhaps twelve or eleven, Rin displays behavior very typical of an abused child prior to her mother's arrival, pleading to be released so that her parents won't know that she's been hospitalized in an effort to maintain the parody of 'normal' she exists in.
Rin is then taken in by Kagura's family, and she lives there for five or six years. Despite this long standing living arrangement, Rin was clearly unable to form meaningful bonds with the family, and Kagura informs Yuki that she is often absent from home and sometimes skips school.
It's clear that she hasn't recovered from the abuse in any meaningful way by her first appearance in the series, nor is it addressed; like most of the Sohma family's ugly secrets, it's swept more or less under the rug and she continues to exhibit classic symptoms of an abuse victim, possessed of a conviction that what was done to her was somehow her fault and if she could only figure out what she'd done wrong, her parents would someday love her again. "In reality, her only 'sin' was being born cursed, to parents who were unable to cope, and whose resentment of her outweighed their desire to fake it".
Rin and Haru were close as kids and remained close as they grew; eventually that friendship evolved into romantic love, and they were clearly deeply emotionally invested in each other; they spend enough nights together that he is the only one who could be close to her while she slept without waking her, and he is used to waking her from nightmares. Haru's inability to understand Rin's actions when she breaks up with him leads him to doubt how well he understands her, but the fact is that he was simply lacking a vital piece of information. It's clear they know each other very well.
Prior to her appearance in the series we know two important facts about Isuzu; that she has suffered something so terrible at Akito's hands that Shigure and Hatori mutually agree they cannot allow anything like it to happen again, and that she previously dated Haru. She dated Haru for some years and was deeply in love with him; when Akito learned of this she attacked Rin, culminating in pushing her out a window some stories above the ground. Though Haru was the one who initiated their relationship and convinced Rin they should act on their feelings, when Akito asks her who made the first move, the question heavy with implicit threat, Rin redirects Akito's wrath onto herself despite the fact that she will suffer great punishment.
This only further supports Haru's assertion to Yuki in chapter 69 that Rin "can be harsh" but won't lie to "protect herself". Indeed, she maintains the falsehood despite the truly frightening level of violence Akito directs towards her. During Rin's lengthy hospitalization she broke up with Haru, only telling him that she was "tired of him" when in reality Akito had emotionally preyed on her poor self-esteem and emotional scars to convince her that Haru was better off without her, unknowingly feeding into her earlier fears that her love would consume, hurt or drive him away.
From this point on Rin is clearly deeply determined to break the family curse and free Haru from Akito.
Rin is complicated; she is aggressive and unkind, wielding words as a weapon to keep people away from her likely due to her history of abuse, but she is also deeply loyal and passionately emotional. She can be tremendously self-sacrificing, but on the other hand is often uncomfortable with displays of emotion, cranky and self-conscious and suffering from painfully low self-esteem. At the point in canon when she makes her appearance, she's clearly disillusioned and questions Tohru's optimism - not aggressively, but almost resignedly. She's penetratingly perceptive and uses this to keep others from seeing her own vulnerabilities; she uses this tactic on both Yuki and Tohru. Haru states that she will not lie to protect herself, and all canon evidence supports this statement.
She fears Akito greatly due to not only the constant overhanging threat Akito clearly presents for all members of the zodiac but also a savage attack that left her mentally and physically scarred, and avoids her whenever possible. Although she isolates herself from others, Rin can occasionally be seen with Hiro because he sees her falling during the attack of Akito. Her other links are with Hatsuharu, Kagura, and Kagura's mother because they visit Rin during her stays in the hospital as a child, as her parents or rather her mother visited her only once: to tell her not to bother coming home. She goes to an all girls' private school, and resides at Kagura's house. Rin suffers from stomach ulcers, and her eating habits are sparse, probably due to stress and trauma.
Rin had long black hair that went past her hips during the Before Summer Vacation Arc until halfway through the After Summer Vacation Arc. Her hair was cut short by Akito as a punishment on trying to steal her box. She tends to wear revealing clothes with a Gothic style. She also has dark brown (sometimes depicted as black) eyes. The accessories she wears are made by Haru. Her height is approximately 5'4"-5'5", almost the same as Uotani. But shorter by 1-3 inches (noticed when she was walking together with Tohru in chapter 107).
Fruits Basket Manga
Before summer vacation, Isuzu was walking around town in search for Akito Sohma and Kureno Sohma. Isuzu was not feeling well at that time and was trembling.
During summer vacation, Izusu arrives at the villa where the Sohma's along with Tohru Honda was staying. Tohru's sheets were blown away to Izusu's location in the woods. Once Tohru finds her sheets, she meets Izusu in her possessed form of a horse. Although it didn't take Izusu long to change back, Yuki Sohma arrives to assist, however Izusu rejects the help. She threatens Yuki that if he tells Hatsuharu Sohma anything about their meeting, she would kill him.
Hatsuharu appears to Isuzu after summer vacation and talks to her about their break up. When the conversation ended, Isuzu walks up, but Hatsuharu stops her and kisses her on the spot. Izusu slaps Hatsuharu and leaves .
Her mother visited her only once: to tell her not to bother coming home.
As younger children, Haru would visit Yuki in his isolated room, which was forbidden. Rin felt that she needed to protect him, and so she would go with him, making excuses to leave right before some adult discovered Haru in the room.
Haru and Rin knew each other from childhood and were very close during that period; he found her when she collapsed, and stayed with her in the hospital, ferociously defending her when her mother dropped by for the last time to deliver some final abuse. They fell in love and Haru eventually convinced Rin, who was terrified of Akito, to take the risk and act on their feelings for each other.
After Akito's violent physical and emotional attack, during which she convinced Rin that their relationship would hurt Haru and she was no good for him, Rin broke up with Haru, telling him merely that she was "tired of him", obviously aware that if Haru was aware that Akito's assault and Rin's fear for him had spurred her disassociation he would not accept it and at that time, before the curse and the Akito's reins on the Jyuunishi had begun to fracture, his response to learning about Akito's actions could put him in very serious danger.
Rin also attempted to find a way of breaking the Sohma curse for Haru's happiness and freedom from Akito's control, but her efforts were in vain. She became ill and was hospitalized once more; it's implied that this has been a pattern throughout her life. Haru tried to visit her, but she drove him away, even swinging her IV at him to accomplish her goal. After that they were distanced and contact was limited - and understandably forbidden by the hospital staff - but it's undeniable that both of them remained aware of and invested in each other, though Rin was better at concealing her state from Haru than vice versa.
At one point, Akito's mother, tricks Rin into trying to steal a particular box from Akito's room; she promises Rin she will tell her how to break the curse (and thus free Haru) if she does so. She is caught and imprisoned in the cursed cat's room for three or four months by Akito, who cuts off most of her hair. She is freed from her imprisonment by Kureno Sohma, who discovers a maid carrying food into the room; the distressed maid tells him that its occupant has not been eating. She is taken to the hospital suffering from severe malnutrition and the psychological trauma of her confinement.
During this time Haru learns from Hiro that it was Akito who pushed Rin out a window and Rin's true motivation for breaking up with him. Rin escapes from the hospital in a daze and is later found semi-conscious on the street by Haru. She believes she is hallucinating and has been dreaming the entire release from the cat's room - the dialogue implies a history of ill-health to this extent - and breaks down, confessing her feelings and that she's failed to free him. He asks her to come home to him, a bit of narrative symmetry considering that Takaya states Haru is Rin's "home" - and she says that it would be good if she could, and that this is a good dream. He tells her it's real, awakening her to reality, and she makes no attempt to lie to him afterwards. He takes her to Kazuma Sohma's house, where she has since been staying while she recovers, and in their next appearance their relationship has clearly resumed.
Kagura's family decided to take in Rin after her parents rejected her completely. Despite being cared by Kagura and her family for years, Rin still remains hostile towards them. Kagura worries often of Rin's health, knowing that Rin falls ill easily.
Rin evidences conflicted emotions regarding Tohru. She rejects and harbors resentment towards what she sees as Tohru's interference in the family; Tohru is an outsider and Rin believes she cannot and will not understand how she and the rest of her family feels. However, internal dialogue reveals that as early as their first meeting Rin is also possessed by the same desire that many of the Jyuunishi develop; to fall into Tohru's arms and be comforted. Her view of Tohru as a maternal figure manifests to the extent that on the verge of fainting she mistakes Tohru for her mother and responds with utter terror, cowering and pleading for forgiveness before she loses consciousness. Eventually Rin's physical distress, despair and torment culminate in her breaking down sobbing in Tohru's embrace.
Though she never evidences such extreme vulnerability again, her previously aggressive behavior softens and it is clear she cares for Tohru deeply. Kazuma commented that Tohru became Rin's first friend, being the first one outside of the Sohma house to become worried about her and how she hates herself
Like the rest of the Sohma family, Rin has a very strained and abusive relationship with Akito. However, unlike the other members, her relationship is worse by comparison. Since she resembles Akito's mother with a similar appearance, Akito had spitefully nicknamed her "Rin", which everyone seemed to adapt to. Other than that one unfortunate coincidence, she had also made love to Hatsuharu, which was different than the other Sohma members who developed feelings for someone within or outside of the Zodiac. This resulted in Akito pushing Rin out of a window, which sent her to the hospital. Rin eventually broke up with Hatsuharu because she feared Akito would do something far worse. Later, when she tried to steal Akito's box, on Ren's orders, she was caught and Akito forcefully gave her a haircut.
Rin was tricked by Ren into thinking that by stealing a box from Akito will then Ren tell her how to break the curse. It was not shown whether Rin has any grudge against Ren. However, she was shown to be shocked when Shigure revealed that Ren was using Rin and there was no way Ren would know how to break the curse.
When Rin was younger, she stayed at Kazuma's house. Due to her background, Kazuma cared for her deeply. This started off with a staring game as Kyo had become jealous over Rin becoming Kazuma's "number one student". Their relationship is slightly bitter. However, over time, they have stopped the game and ignore each other most of the time.
Hiro had witnessed Akito pushing Rin out of the window. Due to that, it led him to constantly worrying about Rin, even visiting her many times in the hospital with flowers, always looking out for her.
Rin asks Shigure for information about the curse, specifically how to break the curse. She feels that Shigure knows because he is the closest to Akito. They appear to be dating in the manga for awhile but she goes back to Haru.
- Unnamed Parents (Estranged)
- Sohma Kagura (Cousin/Foster Sister)
- Sohma Hatsuharu (Boyfriend)
- Honda Tohru (Best Friend)
- She doesn't appear in the anime.
- Even though she doesn't appear in the anime, her Zodiac sign is mention by Shigure when he explains the curse to Tohru.
all information on Sohma Isuzu came from http://fruitsbasket.wikia.com/wiki/Isuzu_Sohma